# A bit different DiY CO2 System



## No.92 (May 1, 2016)

Hoppy said:


> MCSLABS posted a very interesting DIY CO2 system that could be shut off at night, and that has had me thinking about how I would do this if I wanted to try it. My goal would be, as his was, to be able to shut off the CO2 at night, but also to try to make the bubble rate be more consistent between recharges of the yeast/sugar mixtures. Here is what I have come up with:
> 
> 
> 
> ...


Why bother with this complicated setup? Use the Citric Acid and Baking Soda method and you'll never have to worry about rising pressure when shutting off the CO2 at night plus you get instant CO2 right from the get-go. You'd have a 2 bottle system and just add your solenoid to the setup.

You can check out this thread from where I started to post to get an idea what I was doing:
http://www.plantedtank.net/forums/2...tric-acid-baking-soda-co2-40.html#post9204113


----------



## Hoppy (Dec 24, 2005)

No.92 said:


> Why bother with this complicated setup? Use the Citric Acid and Baking Soda method and you'll never have to worry about rising pressure when shutting off the CO2 at night plus you get instant CO2 right from the get-go. You'd have a 2 bottle system and just add your solenoid to the setup.
> 
> You can check out this thread from where I started to post to get an idea what I was doing:
> http://www.plantedtank.net/forums/2...tric-acid-baking-soda-co2-40.html#post9204113


The citric acid method can get pretty expensive and from everything I have read, it can need recharging more often than this system would. Sugar and yeast are very easy to buy, compared to citric acid. And, I'm not sure the CO2 bubble rate can be kept consistent throughout the life of each charge. Failing to do that opens the door for BBA attacks.


----------



## No.92 (May 1, 2016)

Hoppy said:


> The citric acid method can get pretty expensive and from everything I have read, it can need recharging more often than this system would. Sugar and yeast are very easy to buy, compared to citric acid. And, I'm not sure the CO2 bubble rate can be kept consistent throughout the life of each charge. Failing to do that opens the door for BBA attacks.


Well, I bought in bulk. Yes in the long run it is more expensive than a pressurized CO2 system, but I don't know how much you spend on yeast and sugar.

Here is baking soda:





Here is the citric acid:





The citric acid is more expensive per pound but should last quite a while.

The bag I got is probably good for like 9 regular cycles (200g each).


----------



## Hoppy (Dec 24, 2005)

I may switch to a citric acid method at some later time, probably when I'm bored with this method.

In case anyone thinks a DIY CO2 system is essentially free, other than the sugar and yeast, I spend about $51 today, just on parts! That is bottle caps, from Ebay, a solenoid valve from Ebay, 5 check valves from US Plastics, a drop checker from Ebay, and a 2 liter bottle of lemon-lime carbonated water - cost not included, and more bottles needed. Put the word "tech" in a planted tank design and the word "cheap" is never again appropriate!


----------



## Hoppy (Dec 24, 2005)

I just realized that you can store CO2 by dissolving it into water - making carbonated water. So, this system can be simplified to:










With the solenoid valve closed the generated CO2 bubbles into the storage bottle, building up the concentration of CO2 in that bottle, since it has nowhere else to go. Assuming that the solenoid will be off for 16 hours a day, and the yeast solution generates one bubble of CO2 per second, each about 1/16 inch in diameter, you could get about 1.8 grams of CO2 per day stored in the bottle. Each bubble would be about 17 cubic millimeter in volume, which is 980 milliliter of CO2 per day. If all of that dissolves into 2 liters of water, that water will contain about 880 ppm of CO2.

If this is used to supply CO2 at 1 bubble per second to the tank, by opening the solenoid valve and adjusting the needle valve, it would be about twice what is needed for the 8 hour day. If the bubble rate is doubled to 2 bubbles per second, it supplies all that the tank needs for one day, so at worst it gives you one more day off each charge of the yeast sugar bottle. But of course the yeast doesn't stop generating CO2 while you are using the stored CO2, so you could get a bit more than 2 bubbles per second if you wanted. At some bubble rate the stored CO2 won't be adequate for maintaining a steady bubble rate.

I think I will try this scheme first!

EDIT: It would also be possible to sit the storage bottle in a pan of water, with a small heater in it, with the heater being powered when the solenoid is open, or when the photoperiod begins. That would increase the delivery rate of the stored CO2.


----------



## burr740 (Feb 19, 2014)

This is very intriguing, interested to see how it works.

How did you arrive at 1/16 dia bubbles? Im thinking they are going to be bigger. At least all my DIY set-ups I would say closer to 3/16 - 1/4"

Something else I wonder, are all 1/16" bubbles the same? For example, bubble size is affected by how much resistance is at the diffuser, relative I suppose to how much pressure the system is generating (eg working pressure)

So is a 1/16 bubble with zero resistance (open co2 line with no diffuser) equal to a 1/16 bubble with a diffuser that requires 30 psi to crack? By equal I mean containing the same amount of co2


----------



## Hoppy (Dec 24, 2005)

I am only guessing about the CO2 bubble size, mostly because it will vary considerably. I did it just to get a ballpark estimate on whether it can work or not. I also left out the CO2 exit line from the storage bottle, and corrected that.

I plan to use this with a very simple diffuser in the tank, possibly a piece of bamboo chop stick. The back pressure from this will be very low. I suspect the primary back pressure source will be check valves, which take about 1/2 psi to open. My experience with these has been that they stay shut until the pressure builds up then they burp out a single big bubble and shut again. I'm hoping that by keeping the check valves below the needle valve I can limit that burping, which makes an annoying noise.

It is also very possible I am overlooking something obvious and this won't work at all!


----------



## Beamer (May 5, 2016)

Hoppy, Give it a go, it might work but I don't think it will be dramatically better than an empty buffer tank as you are still just storing over production by compressing the CO2 in the pressurised tank which is what a buffer tank does. I think it will have created a vacuum in this pressurised tank if you ever managed to get it into the condition shown in the second diagram and this would stop the flow. Have a look and Andy the minions system I posted about last month and you will see he has solved this problem, it also increases the amount of water that is displaced (therefore the storage capacity) and regulated the CO2 pressure as well.
I have built one of these and it is working very well, the CO2 flow rate is set by the height of the storage tank and it is very stable. Andy even did the pressure calculation and storage capacity.

http://www.plantedtank.net/forums/20-diy/1040073-yeast-co2-system-can-turned-off-night.html


----------



## MCSLABS (Apr 19, 2016)

This may help.

solubility - What is the carbon dioxide content of a soda can or bottle? - Chemistry Stack Exchange


I think either would work but for safety reasons I would put a high cracking pressure check valve on the whole system.


----------



## Hoppy (Dec 24, 2005)

Beamer said:


> Hoppy, Give it a go, it might work but I don't think it will be dramatically better than an empty buffer tank as you are still just storing over production by compressing the CO2 in the pressurised tank which is what a buffer tank does. I think it will have created a vacuum in this pressurised tank if you ever managed to get it into the condition shown in the second diagram and this would stop the flow. Have a look and Andy the minions system I posted about last month and you will see he has solved this problem, it also increases the amount of water that is displaced (therefore the storage capacity) and regulated the CO2 pressure as well.
> I have built one of these and it is working very well, the CO2 flow rate is set by the height of the storage tank and it is very stable. Andy even did the pressure calculation and storage capacity.
> 
> http://www.plantedtank.net/forums/20-diy/1040073-yeast-co2-system-can-turned-off-night.html


Very good! I had read this before, but didn't consider how much of the CO2 would be dissolved in the water, thus not occupying any of the "air space" in the bottle. This is all still a little fuzzy in my brain, but it looks like the rise in pressure with this isn't enough to be concerned about. Tomorrow I will probably have another surge of thinking and make more changes to my idea.



MCSLABS said:


> This may help.
> 
> solubility - What is the carbon dioxide content of a soda can or bottle? - Chemistry Stack Exchange
> 
> ...


Thank you! I read a lot of articles on this subject, but this one seems to be the easiest for me to work with. I need to visit the EBAY and see what bargains are possible for a relief valve. Each time I do this I relearn that however cheap one thing is, when you have 10 things it is no longer cheap.


----------



## MCSLABS (Apr 19, 2016)

Cheapness is why I went with a sealed air pump in which I drilled a hole in the top and sealed an intake tubing to it. I had the pump, the valves and the check valves on hand. I did purchase the silicone tubing though


----------



## Hoppy (Dec 24, 2005)

MCSLABS said:


> Cheapness is why I went with a sealed air pump in which I drilled a hole in the top and sealed an intake tubing to it. I had the pump, the valves and the check valves on hand. I did purchase the silicone tubing though


Ebay does have a CO2 relief valve listed, for about $7 when you add in the shipping. It is a 60 psi relief valve, which would be more than adequate since those carbonated drink 2 liter bottles can hold over 100 psi reliably. But, since the amount of CO2 that will dissolve in water goes up as the pressure goes up, there might not be an overpressure problem. Tomorrow I will see if I can figure it out. I hope someone who has studied this subject more recently will beat me to it though.

I think I will assume the CO2 bubbles are 1/8 inch in diameter instead of 1/16 inch, which means the total amount of CO2 produced to get 1 bubble per second goes up by a factor of 8. That makes the probability of overpressure go up too.


----------



## MCSLABS (Apr 19, 2016)

this might help


----------



## Hoppy (Dec 24, 2005)

Storing CO2 by dissolving it into water doesn't seem to be very efficient. The solubility of CO2 in 20 C water is about .9 ml per ml of water, but the same ml of volume without water will store 1 ml of CO2. The solubility of CO2 in water doesn't increase very much for pressures up to a few atmospheres. And, it is much simpler to store the gas undissolved in water.

If the typical 2 liter bottle of yeast/sugar/water will produce one 1/8 inch diameter bubble per second, it is producing about .033 ml of CO2 per second. That is .033 x 3600 or about 120 ml per hour. 2 liters is 2000 ml, so the time required to produce 2 liters of CO2 would be about 2000/120 or 16 hours. If I have the C02 running for 8 hours a day, I will need to store 16 hours of CO2 production per day. Here is my latest version of this system:










The 60 psi relief valve would keep the pressure in the bottle on the right at 60 psi, so all of the bottles would be at 60 psi. Of course all relief valves are notorious for leaking, so the chances of this working for very long aren't very good.

One thing I like about this scheme is that the water in the first bottle displaces the air in the bottle, so after one day the CO2 being stored would be near 100% CO2.

One thing I don't like about it is that if the yeast/sugar/water bottle produces a lot more or less than one bubble per second of CO2 this might not work very well at all. And, using something like 5 bubbles per second going into the tank might make it run out of CO2, or be very hard to maintain a constant.

I plan to make this and set it up on the kitchen counter first to watch how it works. At least it will be a lot of fun.:smile2:


----------



## pinkkiwi1230 (Feb 15, 2016)

I love the idea, I'm gonna follow this to see how it turns out. I use yeast and sugar. I've checked into using a tank, and yes in the long run its cheaper. But it's at least a year before you come close to evening out on the price . I also just leave my co2 on all the time cause my tanks nothing fancy but just looking at ideas and creativity is fun for me.

Sent from my SAMSUNG-SM-G920A using Tapatalk


----------



## AWolf (Jun 13, 2014)

Very nice. I can see where the reactor could be replaced by breath.


----------



## Sharon_hazan (May 5, 2016)

use the citric acid method more pressure


----------



## Hoppy (Dec 24, 2005)

Sharon_hazan said:


> use the citric acid method more pressure


Perhaps more pressure, but at more cost. The goal is to be able to get more CO2 time on a yeast charge, and turn it off except for the photoperiod. Citric acid systems are inherently able to be shut off when you want to.

Also, I enjoy trying to make a better yeast/sugar system, and fun is the goal of any hobby.


----------



## Sharon_hazan (May 5, 2016)

Hoppy said:


> Perhaps more pressure, but at more cost. The goal is to be able to get more CO2 time on a yeast charge, and turn it off except for the photoperiod. Citric acid systems are inherently able to be shut off when you want to.
> 
> Also, I enjoy trying to make a better yeast/sugar system, and fun is the goal of any hobby.


roud:


----------



## Hoppy (Dec 24, 2005)

These are my costs so far! About $80 for the hardware of a DIY CO2 system! I could have gone a little cheaper, but this isn't cheap now.

I have much of the system assembled now, with the solenoid valve and needle valve still to arrive. I used burr740's method http://www.plantedtank.net/forums/2...-others-build-thread-performance-reports.html for running the CO2 tube thru the lid of the bottle holding the yeast/sugar/water solution, primarily because I have been wanting to try it out, but also because I ordered one too few of the Ebay bottle caps.


----------



## No.92 (May 1, 2016)

Hoppy said:


> These are my costs so far! About $80 for the hardware of a DIY CO2 system! I could have gone a little cheaper, but this isn't cheap now.
> 
> I have much of the system assembled now, with the solenoid valve and needle valve still to arrive. I used burr740's method http://www.plantedtank.net/forums/2...-others-build-thread-performance-reports.html for running the CO2 tube thru the lid of the bottle holding the yeast/sugar/water solution, primarily because I have been wanting to try it out, but also because I ordered one too few of the Ebay bottle caps.


So this is what I paid just recently for my pressurized setup:

Bubble counter ($18):
Amazon.com : CO2 Bubble Counter & CHECK VALVE -aquarium Brass Regulator DIFFUSER Solenoid reactor plants tank : Pet Supplies Amazon.com : CO2 Bubble Counter & CHECK VALVE -aquarium Brass Regulator DIFFUSER Solenoid reactor plants tank : Pet Supplies 
CO2 Reactor ($21):
Amazon.com : External CO2 Ceramic Reactor Diffuser 16/22mm for Aquarium Plants Spiral : Pet Supplies Amazon.com : External CO2 Ceramic Reactor Diffuser 16/22mm for Aquarium Plants Spiral : Pet Supplies 
20lb tank ($115):
Amazon.com: 20 lb CO2 Tank - New Aluminum Cylinder with CGA320 Valve: Kitchen & Dining Amazon.com: 20 lb CO2 Tank - New Aluminum Cylinder with CGA320 Valve: Kitchen & Dining 
CO2 Regulator/Solenoid/Needle Valve ($95):
Amazon.com : U.P. Aqua Co2 Regulator for Aquarium : Aquarium Air Pumps : Pet Supplies Amazon.com : U.P. Aqua Co2 Regulator for Aquarium : Aquarium Air Pumps : Pet Supplies

Here is the link to the other thread where I describe this setup:
http://www.plantedtank.net/forums/9...z-paintball-tank-vs-5lb-tank.html#post9296505

I'm missing a couple of things from there like the extra hose to attach the inline CO2 reactor ($22) and the digital timer ($14). So about $250 without these 2 things (in case you already have it).

Also, I hope that tubing you bought was for CO2? CO2 requires a different type of tubing that can handle the higher pressures (or so I've read)


----------



## Hoppy (Dec 24, 2005)

No.92 said:


> Also, I hope that tubing you bought was for CO2? CO2 requires a different type of tubing that can handle the higher pressures (or so I've read)


No, just ordinary silicone air tubing works fine with CO2. When the tubing is that small in diameter the forces involved with pressures up to 100 psi or more aren't enough to justify stronger tubing. I have used it before with no problems.

One reason my costs seem so high is because I included everything in the total, where pressurized CO2 system cost that most people report only includes the basics. All of the cheap little hardware stuff always adds a lot more to the cost than we expect. But, even knowing this, I was still shocked at how much it was. That has been my experience with all of my DIY projects.:grin2:


----------



## Hoppy (Dec 24, 2005)

I went back to the posts on this subject that inspired me to try this. My design is almost exactly the same as Andy the minion's: http://www.plantedtank.net/forums/2...ystem-can-turned-off-night-2.html#post9219850 except I plan to use the stored air in the storage bottles to pressurize the CO2, instead of keeping the storage bottles high enough above the rest of the system to get a "head" pressure. When I try this in my spare bathtub I should quickly learn if it can be done this way.


----------



## Nordic (Nov 11, 2003)

What do you guys do in winter? My yeast bottles are such a pain when it is cold. If wouldn't be another addition to my power bill I would have put it in a tank with a heater to keep it warm and productive.


----------



## Hoppy (Dec 24, 2005)

I live in an apartment, rather small, so the cost of heating in the winter isn't much. We keep the temperature around 72-75F. Not a problem for the yeast. I have considered putting the generator bottle in a water bath, with a small heater to keep it warmer, but I haven't tried that yet.


----------



## Nordic (Nov 11, 2003)

It is the middle of winter yet we two days of 82 degree plus weather, my new bottle seems to be picking some speed up now.
Total cost, old cooldrink bottle, centre from a broken airstone and some teflon tape., You know Do It Yourself, rather than Buy It Yourself.


----------



## No.92 (May 1, 2016)

Hoppy said:


> No, just ordinary silicone air tubing works fine with CO2. When the tubing is that small in diameter the forces involved with pressures up to 100 psi or more aren't enough to justify stronger tubing. I have used it before with no problems.
> 
> One reason my costs seem so high is because I included everything in the total, where pressurized CO2 system cost that most people report only includes the basics. All of the cheap little hardware stuff always adds a lot more to the cost than we expect. But, even knowing this, I was still shocked at how much it was. That has been my experience with all of my DIY projects.:grin2:


So what you didn't include in the price is the materials. Yeast and sugar or Citric Acid and Baking Soda. How much are those monthly or yearly? I calculated it for my 125G tank and it would be something like $25 per 3 months, whereas my 20lb CO2 tank probably needs 1 refill every 8 months to a year (I won't know until the next refill). So might end up being quite a bit more.


----------



## Nordic (Nov 11, 2003)

Largest tank I ever DIY CO2ed was a 26gal, and that was a perpetual seesaw of more algae, then less algae.


----------



## Hoppy (Dec 24, 2005)

I noticed that I need a way to avoid having the 3rd bottle pressure drop below atmospheric pressure, so I added a check valve to let more air in when necessary. I will have a lot of possible leakage sites, so eliminating leaks may be a difficult job.

My total cost is now $88 after I bought a female pipe thread to tube barb adapter to connect the relief valve.

No doubt, a pressurized CO2 system costs less to operate over a year or so of operation. But, the initial cost is often out of reach for us. I only expect to use this system for a year or so, if that, so there is no savings for me to buy the regulator/tank/etc. for a pressurized system. This largely a fun project, secondarily a CO2 source to see what effect it has on my current tank and plants. I want about 10-20 ppm of CO2, at most. The light intensity I have doesn't make it necessary to have more than that - I think.

This low CO2 level also means I need to use a drop checker that lets me know if I'm in that range, and not way below or way above it. 4 dKH water won't do that. I haven't decided what KH I will use.

EDIT: If I use 1 dKH water in the drop checker it should be green to yellow green at 7-12 ppm, and bright yellow at 30 ppm. I will use Cardinal's keeper's method as described in http://www.plantedtank.net/forums/1...rating-test-kits-non-chemists.html#post801218 to make the 1 dKH water.


----------



## Beamer (May 5, 2016)

Hoppy,
I just did the calculation of CO2 dissolved in your 2 litre bottle. I took the 100psi figure you quoted earlier, this is probably a maximum value and may not be practical as a coke bottle is typically 35psi
The dissolved CO2 concentration at 25°C = Pressure (atmospheres)/Henrys law constant for CO2 = 6.8/29.76 = 0.228mol/litre and you have twice this in your 2 litres.
1mol of CO2 = 44g so 2litres would contain 2x0.228x44 = 20grams of CO2. This can also be calculated as a volume of CO2 at normal pressure using the perfect gas law V=nRT/P
So at 1 atmos your 100psi of 2x0.228mol dissolved gas would become 11 litres of CO2 You only get this store 'back' when you reduce the pressure to atmospheric pressure and the system stops bubbling CO2 well before that.
BUT For the store to work the high pressure and more importantly a large fluctuation in pressure is needed, and fluctuating pressure are very bad for a restrictor based bubble limiter. Incidentally if you do the same for coke bottle pressures this reduces to 3.9 litres of CO2

If you did the same calculation of stored CO2 using just an empty buffer tank you would get V2=(P1xV1)/P2 So again at 100psi and a 2 litre bottle this gives a CO2 store of 12 litres of CO2, again its entirely dependant on maintaining the very high pressures, coke pressures drop this to 4.2 litres of CO2

So, yes it will work but indeed its not massively different to a simple buffer tank. I think the holy grail of a DIY switchable and controlled yeast (or Soda/acid) system is still a low regulated pressure with a store.


----------



## Hoppy (Dec 24, 2005)

Beamer said:


> Hoppy,
> I just did the calculation of CO2 dissolved in your 2 litre bottle. I took the 100psi figure you quoted earlier, this is probably a maximum value and may not be practical as a coke bottle is typically 35psi
> The dissolved CO2 concentration at 25°C = Pressure (atmospheres)/Henrys law constant for CO2 = 6.8/29.76 = 0.228mol/litre and you have twice this in your 2 litres.
> 1mol of CO2 = 44g so 2litres would contain 2x0.228x44 = 20grams of CO2. This can also be calculated as a volume of CO2 at normal pressure using the perfect gas law V=nRT/P
> ...


What I read on various websites is that typical Coke bottles withstand over 120 psi. With a 60 psi relief valve I should be safe. I wish I could say this has to work, but I can't, so I will test it in a bathtub for a few days first.


----------



## Beamer (May 5, 2016)

Hoppy Go carefully -a workshop airline is at about 100psi and that uses reinforced tubing Your 4mm silicon tube is a lot smaller so it dosnt have to be as strong never-the-less 100psi will be asking a lot of it and if it fails it will be a connection or the tube itself. I dont doubt it is possible for yeast to get a system to 100psi my fear is that it will be really difficult to maintain the pressure due to leaks. Please fit a pressure gauge plus a bubble counter and record the experiment, it will be facinating. Best of luck


----------



## Hoppy (Dec 24, 2005)

The hoop stress for thick wall tubing is about equal to the pressure it is subject to times the ratio of the sum of the squares of the outer and inner diameters to the difference between the outer and inner diameters squared. Silicone air tubing is about 1/4 inch outer diameter and 3/16 inch inner diameter, so that ratio is about 3.7. At 100 psi the hoop stress will be about 370 psi. But, silicone rubber has a tensile strength of about 1600 psi. This means the tubing isn't likely to burst at 100 psi, let alone at the 60 psi pressure the relief valve should limit it to.

What is more likely is that the connections will blow apart. The force the internal pressure exerts to blow the connection apart is the pressure times the internal area of the tubing or, at 60 psi, about 1.7 pounds. If the hose barbs are shoved far enough into the tubing I doubt that that load will blow the connections. I may not have the barbs inserted far enough, since I couldn't find an adapter for the pressure relief valve that was the right size and I'm using a little oversized one.

Leakage is much more likely, especially because very minute leakage is enough to dissipate all of the CO2.

All of this is why I'm going to test this in a bathtub first. The pressure build up, if it even occurs, will be very slow, so any leakage will probably eliminate any pressure buildup. I think even if this passes my testing, once it put it in use the aging of the tubing may end up causing it to fail after a year or so. That possibility still has me worried. A failure would probably just spray the water in the bottles all around, about a gallon of water.

EDIT:
I just tried another way to calculate how much CO2 I can store in the 2 liter storage bottle. Unless I made a big decimal point error the result is shocking!

Assume the CO2 generated by a 2 liter water/sugar/yeast bottle is one bubble per second, and each bubble is 1/8 inch in diameter. The volume of each bubble will be 4 pi times 1/16 inch cubed, divided by 3, which is 9.8 x 10^-4 cubic inches. That is 16 cubic millimeters, or 16 times 10 to the minus 12 liters. The density of CO2 at one atmosphere is about 2 gram per liter. So each bubble contains about 16 x 10 to the minus 12 times 2 grams of CO2. That is 32 times 10 to the minus 12 grams.

As the bubbles of CO2 accumulate in the storage bottle the pressure in that bottle increases until the air in the pressurizing bottle rises to 60 psi guage or 75 psi absolute, which is 5 atmospheres. At 5 atmospheres the amount of air in the pressurizing bottle is compressed to 1/5 of the original volume, or 0.4 liters. So, 1.6 liters of the storage bottle is filled with CO2, at 5 atmospheres absolute pressure. The density of CO2 at 5 atmospheres is about 10 grams per liter. 1.6 liters of CO2 at that pressure is about 16 grams of CO2.

The time it takes the CO2 generated at one bubble per second to accumulate to 1.6 liters at 5 atmospheres is 16 grams divided by 32 times 10 to the minus 12 grams per second, or 5 times 10 to the 11th power seconds. And that is 1.4 times 10 to the 8th power hours, or 6 million days!!

Based on that, and assuming no big decimal point error, the relief valve will never ever open, and the pressure in the bottles cannot ever be more than a few psi. I haven’t tried to calculate what that pressure should be - some calculus involved there.

Did i make a massive error in this calculation?


----------



## Beamer (May 5, 2016)

Hoppy
Sorry Hoppy I'm not trying to be an a**e about this but strongly in a spirit of cooperation I would disagree, those tube burst pressures seemed way too high so I looked up a spec sheet. Safe working is 5psi and I would expect deformation of such a soft material would make the connection method critical to get a reliable seal even at this pressure.
Secondly on your CO2 generation rate assumptions (again sorry) I think the you have taken a typical CO2 USAGE rate as being the yeast production rate but I think yeast can easily exceed this rate, maybe by an order of magnitude, especially if you use multiple generators. I didn't have time to check the calculation.
I don't have firm data on CO2 generation rates but if your assumptions are correct bottles would never burst and we know they do, so I still advise caution.
I'm a big advocate of having at very least a buffer tank in any DIY CO2 system and it is for exactly this reason, more volume means lower pressure increase with over production. I don't know what the people who have had explosions were using, maybe they just have the volume of 3ft of tube..... and then close a valve.
I still have an Andy the minion system set up so I can accurately measure the rate of CO2 generation (with the valve closed the rate of increase of water in the buffer tank is exactly this). I will try to get around to doing some measurements, but this will be a 'round tuit' job but I will post if I get anything that seems worthwhile.


----------



## Hoppy (Dec 24, 2005)

Thank you Beamer! That table for silicone tubing isn't at all promising, unless my calculations are correct (I doubt it), in which case the pressure would never get much above 15 psi, if even that high. I'm still trying to calculate the pressure vs time at about one bubble per second, and I'm still confused. 

Now that I have all the parts for this I will soon have it set up in the bathtub to see what really happens. I much prefer to have calculated what will happen before I test it, but that may not work out.

I agree that you can get a pretty high bubble rate out of a DIY CO2 system, but I plan to aim for no higher a bubble rate than I need, adjusting it by how much yeast I use in the bottle.


----------



## No.92 (May 1, 2016)

All this math hurts my head


----------



## Beamer (May 5, 2016)

Good on you Hoppy! The fun is in the journey, but don't put yourself in the record books as the first manned bathtub in space  because it doesn't look like No92 is offering to calculate the orbital mechanics or your re-entry point - For shame No92


----------



## Hoppy (Dec 24, 2005)

I think I have correctly calculated the pressure of the CO2 vs time at 1 bubble per second CO2 production! It is:










Assuming no big errors in this, it should work very well.










The system is now set up in the bathtub, minus the solenoid valve.


----------



## Beamer (May 5, 2016)

Hoppy, I checked the calculation and I think there is an error somewhere. Based on your 1/8" bubble/sec after 18 hours I think you will have 29.3psi in a 2 litre buffer tank if you start from an empty bottle. This is because a bubble a sec is 0.2litres per hour so at the end of 18 hours you will have added almost 4 litres of CO2 into your 2 litre bottle. Obviously day two will get interesting - as you consume as much as you generate so it will only 'lose' 8 hours of not putting more into the buffer, when you close the valve at the end of the second day you will still have 29.3 psi in your buffer. At the end of night 2 you will have 9 additional litres in the buffer 58.4psi !
Obviously there are a lot of assumptions in this, that there are no leaks, constant generation, constant flow through the needle valve etc, none of which will be true. It also ignores the CO2 dissolving into the goo in the generator and water in your buffer but based on this I can certainly see why bottles explode.

How's the head No92? 

Hoppy you updated your post and changed the calculation while I was doing the calculation, the numbers are much closer now, I wouldn't argue the differences, but still remember days two, three and four


----------



## No.92 (May 1, 2016)

Beamer said:


> Good on you Hoppy! The fun is in the journey, but don't put yourself in the record books as the first manned bathtub in space  because it doesn't look like No92 is offering to calculate the orbital mechanics or your re-entry point - For shame No92


And I'm an engineer too. I didn't say I couldn't do it. Just saying my head hurts. I thought taking care of fish/plants was suppose to be a fun hobby. Not require advanced math. 

Bump:


Hoppy said:


> I think I have correctly calculated the pressure of the CO2 vs time at 1 bubble per second CO2 production! It is:
> 
> 
> 
> ...


If those are those cheapy plastic T-connectors, they will probably pop right off when pressures increase. I bought some of those and they don't work well at all.

You're better off with this metal T connector: 

https://www.amazon.com/gp/product/B00WWC04DC/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1


----------



## Hoppy (Dec 24, 2005)

The T connectors are sold for drip irrigation systems. They have worked for me before, but not at pressures above atmospheric. That's one of the reasons for the bathtub test.

Beamer: remember, the CO2 production should remain virtually constant in grams per second, but the bubbles will get smaller as the pressure builds up, so they occupy less space. That is why a 2 liter bottle can hold more than 2 liters of CO2, when it is pressurized. At 2 atmospheres pressure it holds twice the volume, for example. I rechecked my calculation, which is the result of many failed attempts, and still think it is correct. Another, and the main reason for the bathtub test.

EDIT: The system is working like it is supposed to. It took a long time for the CO2 to start flowing. After it did, the storage bottle began to take in CO2, pushing water into the pressurizing bottle. About 5 hours after I set it up I found the generator bottle felt like it had some pressure in it, so I opened the needle valve, and CO2 gushed through the bubble counter, as water moved back to the storage bottle. I don't want to leave it pressurized over night, so I will close the needle valve tomorrow morning and watch how fast the CO2 accumulates. The height of water in the pressurizing bottle acts as a pressure gauge, so I can estimate the pressure - something I didn't try before I dumped the stored CO2 this time.

Edit: My CO2 bottle mix is 2 cups of sugar, 1/2 tsp of bread machine yeast, 1/2 tsp of baking soda, in a little less than 2 liters of water. The bubble size is about 3/16 inch in diameter, and I get about 4 bubbles in 5 seconds, less than one bubble per second.


----------



## Hoppy (Dec 24, 2005)

The system is still working, but it will not work like I was hoping. As Beamer pointed out, the days following after the first day of use will be a major problem, because the pressure will build up too high in the storage bottle. The only way it can work is if the storage bottle is emptied each day the system works. In other words, the bubble rate to the tank has to be about 3 times the rate at which the yeast bottle produces CO2. That would mean the CO2 going to the tank comes 2/3 from the stored CO2 and 1/3 from the yeast bottle. But, that means the pressure in the storage bottle drops substantially during the day. And, a needle valve can't adjust for that, so it has to be set so the *average* CO2 usage during the day is 3 times what the yeast generates. As the storage bottle runs out, the bubble rate to the tank will drop back to 1 bubble/second (if that is what the yeast generates), but will be much higher when the CO2 first starts flowing to the tank. That is a tricky thing to set up! And, it hardly results in a consistent level of CO2 in the tank water during the photoperiod. Obviously some more thinking is needed.

One thing I have learned is that the water in the storage system absorbs a lot of CO2, becoming club soda! As the pressure drops in the storage bottle that CO2 fills the water with bubbles, just like when you open a bottle of club soda.


----------



## Nordic (Nov 11, 2003)

Try and get that system past the TSA.


----------



## Hoppy (Dec 24, 2005)

Nordic said:


> Try and get that system past the TSA.


The next time I carry on my 65 gallon tank, with this system, I will find out:laugh2:










Solenoid valve moved to depressurize bubble counter when off.


----------



## Hoppy (Dec 24, 2005)

Notice the different water levels in the clear bottles. The right hand one has water pushed over from the middle one as the pressure builds up.

EDIT:
The solenoid valve needs to be upstream of the needle valve to prevent a big surge in CO2 when solenoid opens.


----------



## MCSLABS (Apr 19, 2016)

Looks good, I like the safety valve on the whole thing.


----------



## Hoppy (Dec 24, 2005)

MCSLABS said:


> Looks good, I like the safety valve on the whole thing.


My calculations make me believe that it would take 48 hours of running with no CO2 leaving, before the pressure would reach 60 psi. That is at 1 bubble per second (at atmospheric pressure). Double the bubble rate and it should take 24 hours to reach 60 psi.

If the bubble rate to the aquarium is 3X the bubble rate from the yeast bottle, the storage bottle should be near empty after each 8 hour "on" daily session. Since the storage pressure would not be constant during that 8 hours, it would have to be an average of 3X the bubble rate from the yeast. And, to achieve that average, the highest bubble rate during the 8 hours might be enough to gas the fish. This is leading me to believe I need to reduce the amount of yeast I use by about half. Doesn't that reduce the bubble rate by about half also? If not, what does it take to halve the bubble rate?


----------



## Hoppy (Dec 24, 2005)

This is the set-up after about 18 hours of CO2 generation and storage, with none being used. The pressure in the storage bottle is about 3 atmospheres - 45 psig. No problems.


----------



## Nordic (Nov 11, 2003)

Would be interesting if you had a way of disconnecting the supply bottles without loosing gas, just to see how long the reservoir can pump out CO2. I luckily spotted some brewers yeast in the baking section this weekend. It seems to laugh at it being cold, does make quite a frothy head though.









Maybe we can harness the whole family to collect CO2.


----------



## Hoppy (Dec 24, 2005)

I have the system installed under my tank, in the stand, now. Next, I need to look for a very small internal filter/pump to make a much better reactor. I have the bubbles coming in under a tiny powerhead now, but it is not a stable location.

Nordic, I can disconnect the yeast/sugar bottle and let it run off the stored CO2 if I want to. I have a check valve at the cap on the bottle so I can do that.

The more I play with this the more I see it as an amplifier instead of a battery. It lets me run a much higher bubble rate than the simple one bottle system does, about 3X higher. The problem is that as the stored CO2 is used, the pressure in the storage bottle drops, reducing the flow rate. This is where I miss having a pressure regulator. But, if I run the CO2 to the aquarium for 8 hours a day, I need to average 3X the generator bubble rate to use up the stored CO2 and leave room for the next 16 hours of storage. I get to cram 24 hours of CO2 production into 8 hours.


----------



## No.92 (May 1, 2016)

How how many days can you run your setup at 1bps?


----------



## Immortal1 (Feb 18, 2015)

Really liking the creativity / engineering you have put into this system. When I first saw DIY cO2 I thought to myself - how cave man is this? I could honestly believe the actual cO2 level would vary enough to make algae issues worse instead of better. Your system on the other hand looks lie a very good/stable DIY approach to cO2.


----------



## Hoppy (Dec 24, 2005)

No.92 said:


> How how many days can you run your setup at 1bps?


If I empty the storage bottle every day, the number of days it will run is the same as for a simple DIY system, and based on my experience with this size bottle, with the same mix, that is about one week. But, this may be too much CO2 for my tank, and I may want to use only half the dose of yeast, which might stretch the interval to 2 weeks. I plan to try that as soon as I get my CO2 reactor going - probably 2 days from now. And, there is a difference in how this is acting now that it isn't in the bath tub, a difference I haven't figured out yet. So, who knows??


----------



## MCSLABS (Apr 19, 2016)

Changing the dose of yeast will only delay the onset of fermentation as the yeast will populate themselves once conditions are right. A source of food and pH is what usually kills off the yeast. I toyed with the idea of using marble chips in the bottom of the reactor vessel to stabilize ph as it lowers.


----------



## Hoppy (Dec 24, 2005)

MCSLABS said:


> Changing the dose of yeast will only delay the onset of fermentation as the yeast will populate themselves once conditions are right. A source of food and pH is what usually kills off the yeast. I toyed with the idea of using marble chips in the bottom of the reactor vessel to stabilize ph as it lowers.


That makes a lot of sense. What does reduce the CO2 production, other than lowering the temperature? I assume a smaller bottle will also reduce the production.


----------



## burr740 (Feb 19, 2014)

Alcohol poisoning is usually the first thing to kill the yeast.

More yeast = more co2 for a shorter period of time. Less yeast = less co2 but the mixture will run longer. 

At least this has been my experience.


----------



## Nordic (Nov 11, 2003)

Which is why I always recommend wine or brewers yeast.


----------



## Hoppy (Dec 24, 2005)

burr740 said:


> Alcohol poisoning is usually the first thing to kill the yeast.
> 
> More yeast = more co2 for a shorter period of time. Less yeast = less co2 but the mixture will run longer.
> 
> At least this has been my experience.


So, you haven't noted your yeast "colony" adjusting to match its food supply (sugar), as MCSLABS mentioned?

Does a 2 liter bottle produce CO2 at twice the rate that a 1 liter bottle does?
Does a 2 liter bottle with one cup of sugar produce CO2 at half the rate that it does with 2 cups of sugar?
Does a 2 liter bottle with 1/4 tsp of bread yeast produce CO2 at half the rate that it does with 1/2 tsp, and 1/4 the rate that it does with 1 tsp?
Has anyone experimented to find answers to these questions?

I have always just accepted the common knowledge that more yeast gives higher CO2 production, but the bottle needs restarting sooner. And, more sugar makes the bottle last longer. But, I have never actually experimented to see if any of that is true. (This seems like discussing what the best tire pressure is for a model T Ford!)


----------



## MCSLABS (Apr 19, 2016)

Yeast grow at a geometric rate, so they peak quickly in the environment they are in. As long as there is a food supply, low toxicity, they will keep populating until they crash. More yeast will get the ball rolling sooner than less yeast but the end result would be the same production for a given standard (variables the same). More volume (water, sugar) would mean the ability to increase population higher before either the solution becomes toxic or the food supply runs out. Larger volume means more CO2, The duration however wouldn't follow the same curve (volume/duration)


----------



## burr740 (Feb 19, 2014)

Hoppy said:


> So, you haven't noted your yeast "colony" adjusting to match its food supply (sugar), as MCSLABS mentioned?
> 
> *No, but that's not to say it doesnt hold true. In all my doings, more yeast = more co2 for a shorter run time, less yeast = less co2 for longer.*
> 
> ...


Im not disputing what MCL said, have also seen it explained the same way by many others who should know. Frankly my understanding doesnt run that deep to know exactly what is happening, or why. Scientifically speaking, I may have it all wrong. The above answers in bold are merely what I have personally seen happen from experimenting with different recipes and various number of bottles on several different tanks. tifwiw

Now days I just thank my lucky stars everything is pressurized with just a knob to turn.


----------



## Hoppy (Dec 24, 2005)

burr740 said:


> Now days I just thank my lucky stars everything is pressurized with just a knob to turn.


Any one can turn a knob. But, mixing sugar, yeast, baking soda and water takes a high skill level.:grin2:


----------



## No.92 (May 1, 2016)

Hoppy said:


> If I empty the storage bottle every day, the number of days it will run is the same as for a simple DIY system, and based on my experience with this size bottle, with the same mix, that is about one week. But, this may be too much CO2 for my tank, and I may want to use only half the dose of yeast, which might stretch the interval to 2 weeks. I plan to try that as soon as I get my CO2 reactor going - probably 2 days from now. And, there is a difference in how this is acting now that it isn't in the bath tub, a difference I haven't figured out yet. So, who knows??


1 week? While I applaud your efforts here, but I still recommend going with the citric acid/baking soda method. I was able to run it about 25 days or so with a doubled mixture in two 2L bottles at 1bps. You would also not have had to worry about all this overpressure stuff. Plus you get CO2 instantly once you've set it up. No need to wait for the yeast to eat the sugar or however it works. Also with the citric acid/baking soda method, I could easily achieve double digit bps rate if I wanted. So the amount of CO2 is there for the using.


----------



## Hoppy (Dec 24, 2005)

When I get tired of playing with this set-up, or find that it doesn't do what I want, then I will look at a citric acid/baking soda set-up. Meanwhile I will have exercised my dormant engineering skills, and had a good time.

It looks more and more like my bubble rate is set by the flow resistance of my piece of chopstick. I'm finding that my needle valve has no effect once it is open at all. When I get my Hagen Elite and get it modified as a CO2 reactor I will dump the bamboo piece anyway, or at least make it a lot shorter. Right now I have about a one inch long piece in the end of the CO2 line.


----------



## burr740 (Feb 19, 2014)

I used get about 1 bps for approximately 2 weeks out of a single 2 Liter bottle. This was using a chopstick pre-diffuser going into a powerhead or AQ HOB

2 cups sugar
1/4 tsp regular bread yeast
1/2 tsp baking soda


Having 1 bottle for every 10 gallons of aquarium worked about right. Changing half the bottles every week to stagger things out for better overall consistency.


----------



## Hoppy (Dec 24, 2005)

I have a half teaspoon of yeast, and I get about 1 bubble per second too.

I have my Hagen Elite mini filter set up to be the CO2 reactor - the CO2 bubbles just go through the tiny pump, chopping them into very fine bubbles. I have nothing on the end of the CO2 tube to restrict the flow. With this, I get a 4-5 bubble surge, about once every 4 seconds, like a check valve opening to allow flow every second. The needle valve is wide open, and making a big adjustment to it does nothing to the bubble rate. The stored CO2 doesn't seem to contribute any CO2, even though the amount of stored CO2 does decrease during the CO2 on time. Weird!!

UPDATE:
The system is working much as I expected, except that the CO2 bubbles are released in surges of 4-6 big bubbles every 4-10 seconds. Apparently this is a result of the cracking pressure of the check valves in the system. My drop checker, with 2 dKH fluid in it, is indicating that I have significant CO2 in the water now, probably in the range of 10-15 ppm, as I wanted. Last night the water in the storage bottle was all moved to the presssurizing bottle, so the CO2 pressure was pretty close to the relief valve pressure setting. But, no evidence that it popped open.

And, of course, my plants are growing so fast I'm afraid the tank glass will shatter!!> Maybe part of that is just my optimism, but....


----------



## Hoppy (Dec 24, 2005)

UPDATE:

I found that my system doesn't hold the full pressure that should be there as water moves from the storage bottle to the pressurizing bottle. It does hold some pressure, but no where near the 30-45 psi it should have. Someone predicted this, so I'm not really surprised.

When the solenoid valve opens every day I get a huge surge of CO2 for a few seconds, then it settles down to a regular mini-surge every few seconds. That huge surge blew apart the little Hagen Elite filter once, but not since then. It did panic a fish to take a death dive overboard once too.

I know the CO2 generator bottle has to be approaching a big drop off in production, but the stored CO2 seems to be keeping the bubble rate pretty constant. This may be the secondary benefit of this system. The primary benefit is the much higher effective bubble rate than the generator bottle produces - it acts more like an amplifier instead of a storage system.

I will keep it going for at least a few months to see if I find it worth the expense.

After about a week of CO2 from this system in my 65 gallon tank, giving me between 5 and 10 ppm of CO2 in the water, I can see improvement in the slow plant growth. It isn't spectacular improvement, but definitely some improvement. Based on the knowledge that more CO2 can substitute for some light increase, I expected about what I see.


----------



## kscummins (Jun 22, 2016)

I have a question concerning this system. I am not an engineer; I am however very versed with the chemical and biological reactions taking place. The chemical reaction that is produced by the microbe (yeast fermentation) is as follows:

C6H12O6 => 2 C2H6O + 2 CO2	(Glucose => Ethanol + Carbon Dioxide)

The problem lies with the products of the reaction. We want and use the CO2 being produced, however we do nothing with the C2H6O. This ethanol being produced is the reason that each and every one of your systems crash. Please note any bacterial phase diagram and explanation found online. (No, yeast is not a bacterium, but will proceed through same phases.) In recognizing the problem, it’s time to discuss solutions. 

1.	Some strains of yeast are more tolerant of ethanol levels than others. If you are using baker’s yeast, then it’s time to switch to a brewer’s yeast or wine yeast. (All of the above may contain Saccharomyces cerevisiae. Remember the strain will be different, not the genus and species.) More tolerance of ethanol concentrations will lead to a longer lived colony and therefore a longer lived CO2 reactor.

2.	Removal of ethanol. We cannot remove only ethanol from the system, as this would require distillation and would likewise kill the microbe colony. Although, we can use an additional line ran into the yeast container to extract the ethanol/water/yeast mixture (not all of it) and replace with distilled water. This will reduce the concentration of ethanol within the system and again lead to a longer lived colony and therefore longer lived CO2 reactor. I have not calculated an exact volume to remove as this is dependent on too many variables that are not common among many systems (amount of yeast starter, volume of water, concentration of sugar, volume of CO2 required). I will say this, yeast should be well into the stationary phase after 7 days regardless of all previous variables mentioned. Therefore removal of 50% of volume from yeast container and replacement with distilled water at this time should remove enough ethanol and yeast to send colony back into a small lag or log phase before settling again at a stationary phase. Ideally we want to maintain a stationary phase for secondary metabolite removal, but this would require constant removal of wastes and introduction of nutrients. Most of us want to “set it and forget it” So exchange once a week should suffice, not optimum, but suffice. 

If there is any questions of concerns regarding this post please let me know.


----------



## Hoppy (Dec 24, 2005)

Yesterday I renewed the sugar/yeast/water solution for the first time. I found that even though the CO2 storage bottle was full, it wasn't supplying CO2 to the diffuser. I think that is because of the check valve that needs 1/2 psi to open. That seems like a very small pressure, but it is about 12 inches of water, and I think I have less pressure than that. The pressurizing bottle seems to have a very small leak, so it doesn't let the pressure build up there.

However, even the small amount of CO2 this is producing has made a very visible difference in how fast my plants are growing. With some more fine tuning, and especially some more effort to eliminate leaks, this could work much better. I'm thinking about seeing if one of the aluminum bar type manifolds made for a citric acid system could be adapted to this type of system. That could eliminate many possible leaks.


----------



## Hoppy (Dec 24, 2005)

No.92 said:


> 1 week? While I applaud your efforts here, but I still recommend going with the citric acid/baking soda method. I was able to run it about 25 days or so with a doubled mixture in two 2L bottles at 1bps. You would also not have had to worry about all this overpressure stuff. Plus you get CO2 instantly once you've set it up. No need to wait for the yeast to eat the sugar or however it works. Also with the citric acid/baking soda method, I could easily achieve double digit bps rate if I wanted. So the amount of CO2 is there for the using.


I just changed my CO2 set-up to a vinegar/baking soda set-up: see http://www.plantedtank.net/forums/2...tric-acid-baking-soda-co2-41.html#post9434081 It works much better now! Where I was getting a big burst of bubbles about every 2 seconds, I now get a slightly smaller burst every second. Where it used to start with a huge blast of CO2 when the solenoid valve opened, now it just starts with a normal burst every second. I see no measurable pressure rise in the bottles, so a relief valve isn't needed. I'm guessing this will roughly double the amount of CO2 I get into the water, which is even more than I expected. Time will tell whether this will last 2 weeks or more between recharges, and if it does, this is a much superior system.


----------



## natemcnutty (May 26, 2016)

Hoppy said:


> I just changed my CO2 set-up to a vinegar/baking soda set-up: see http://www.plantedtank.net/forums/2...tric-acid-baking-soda-co2-41.html#post9434081 It works much better now! Where I was getting a big burst of bubbles about every 2 seconds, I now get a slightly smaller burst every second. Where it used to start with a huge blast of CO2 when the solenoid valve opened, now it just starts with a normal burst every second. I see no measurable pressure rise in the bottles, so a relief valve isn't needed. I'm guessing this will roughly double the amount of CO2 I get into the water, which is even more than I expected. Time will tell whether this will last 2 weeks or more between recharges, and if it does, this is a much superior system.


Hey Hoppy! Please keep us updated on how it works for you. Citric acid isn't expensive in bulk, but vinegar is way cheaper. Even if it doesn't last quite as long, I'd much rather go this route! I still have a ton of citric acid to go through, but I'd love a cheaper and easier to source solution.


----------



## sfshrimp (May 24, 2016)

Do you brew beer?


----------



## Nordic (Nov 11, 2003)

You even get brewers yeast at the grocers sometimes, people use it to make ginger beer.


----------



## Albtraum (Dec 27, 2009)

bumping this thread for quality info.


----------



## Hoppy (Dec 24, 2005)

I'm using the citric acid/baking soda method now, and for the past 4 weeks. This seems to work better, but I have still had a few problems with it. The best news I can offer is that even though I rarely have more than 5-10 ppm, nearer to 5, of CO2 in the water, my plants grow very much better and faster. This is what I should have expected if I had studied this scientific paper sooner - http://www.bio-web.dk/ole_pedersen/pdf/Hydrobiologia_2202_477_163.pdf At low light levels the benefit of CO2 starts with almost anything over the 3 ppm we get from the atmospheric CO2, and which soon drops even lower as the plants grow during the day. I have my drop checker filled with 0.5 dKH water now, and that lets me measure the approximate amount of CO2 in the water when it is between about 2 and 15 ppm. I have never had it turn yellow yet, 15 ppm, but it does get to various shades of green, 3-6 ppm. With the 30-35 PAR lighting I have, low light approaching low medium light, there is no reason to try for 30 ppm. And, by dosing Excel (Metricide) daily the fluctuations in CO2 level have not caused an algae attack. My H. corymbosa is now growing about 4 - 6 inches a week, where it barely grew at all without the CO2. And, my crypts are growing much better and looking much more healthy.


----------



## Caelan (Aug 14, 2016)

So. I have a 20 gallon heavily planted tank... Is there anything wrong with using a very simple unregulated system?


----------



## natemcnutty (May 26, 2016)

Caelan said:


> So. I have a 20 gallon heavily planted tank... Is there anything wrong with using a very simple unregulated system?


You mean other than gassing your fish and causing uncontrolled ph swings? =)


----------



## Hoppy (Dec 24, 2005)

If you have low light to low-medium light, as I do, then you may not have a problem using a simple unregulated DIY CO2 system, along with Excel (Metricide). The Excel keeps algae from starting from the swings in CO2 content, and the relatively low light means the plants don't need high CO2 content. Once you determine that the amount of CO2 you get from your system stays below 30 ppm it is unlikely that you risk gassing your fish. A drop checker is one way to make that determination.


----------



## SwissCheeseHead (Dec 24, 2014)

You will need the have a good needle valve, as the citric acid/baking soda system generates enough CO2 to gas your fish. You don't need a regulator.


----------



## Caelan (Aug 14, 2016)

Hoppy said:


> If you have low light to low-medium light, as I do, then you may not have a problem using a simple unregulated DIY CO2 system, along with Excel (Metricide). The Excel keeps algae from starting from the swings in CO2 content, and the relatively low light means the plants don't need high CO2 content. Once you determine that the amount of CO2 you get from your system stays below 30 ppm it is unlikely that you risk gassing your fish. A drop checker is one way to make that determination.


Thanks Hoppy. I have been using sugar and yeast for a year or so now and have never had any problems gassing fish. I average 1 bps at the lowest and 2 bps at the most. My light is considered high but my plants are low to moderate. I was just curious. I like the idea of a regulator though but I am nervous about when I go away for a weekend. I do dose with Excel daily as well as all the other sea chem products as per their suggested dosage. 
My drop checker is on route 

I have a 2.6g Spec I have set up and am trying to figure out the safest and easiest (and cheapest) way to supply co2. But I don't want to hijack your thread ;0P

Nate. Thanks so much for your oh so helpful suggestions


----------



## Hoppy (Dec 24, 2005)

DIY CO2 for a 2.6 gallon tank is very risky. It doesn't take much CO2 to kill the fish in such a small tank. To make that work you would have to find a yeast/sugar mix that produces only a little CO2, like a bubble every 5 seconds, so there is no way it can over dose the CO2 even when you ignore it.

The need for CO2 is more related to how much light you have than it is to the light demands of the plants you use. You need enough CO2 so the plants grow at the rate the light intensity drives them to. If their growth is restricted by a shortage of CO2 you may have unhealthy plants, and that is a sure magnet for BBA and other algae.


----------



## natemcnutty (May 26, 2016)

Caelan said:


> Nate. Thanks so much for your oh so helpful suggestions


Yeah, that's my bad for not reading well (Not enough sleep...). I read your question as not using a needle valve or anything to control CO2 flow, and I was saying that would be a bad idea


----------

