# Co2 fluctuation - Better to use PH Controller?



## MarkMc

I use my controller to get to my target CO2 quicker. The solenoid is on a timer though and shuts it off one hour before lights out and comes on one hour before lights on. You don't need to worry about pH swings due to CO2. You want to see a swing of .5 to 1 each day IMO. A controller is not a necessity though-it's a luxury.


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## Dave-H

I have the exact same problem and I'm trying to figure out how to handle it. I'm considering getting a ph controller, too.

My observation from reading this forum is:

1) many people say that you don't need a ph controller, but nobody explains exactly how to get a stable/good CO2 level without one

2) larger tanks seem harder to get the levels right

3) with all the talk about how easy and safe CO2 is, I read about someone gassing their fish on a regular basis. so a ph controller may be an important safeguard and not just a luxury


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## Hoppy

If you can find a way to set up a pH controller so it actually does maintain a constant level of CO2 in the tank, during the photoperiod only, it could be a good thing. But, the pH in the water doesn't track the ppm of CO2 instantly. There is a lag there too. And, any controller has to allow the pH to vary a little in order to work. Otherwise, it continually hunts - turns on and off every few seconds - which isn't a great idea either. As far as I know most pH controller have a "on" setting and a different "off" setting, to avoid the hunting.

You can't use a drop checker to track how well the pH controller is working, because of the 2 hour lag in response of the drop checker. It just isn't easy to measure/control CO2 without spending a fortune on equipment.

It shouldn't take an hour to get the tank up to the desired level of CO2. You can work on the CO2 delivery/diffusing system to get that time period much shorter, but you will always have a big uncertainty in how much CO2 is in the water, unless you buy some very expensive measuring equipment. Even then, you aren't going to be able to pinpoint the ppm of CO2, because it varies widely around the tank, depending on water circulation, plant uptake rates, loss from the water surface, etc.

Consider reducing the light intensity so the needed ppm of CO2 is low enough to let you safely run it 24 hours a day. Then, the concentration will be a lot more uniform, increasing a bit at night when the plants stop using it, and going back down a bit during the day as the plants start using it.


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## Dave-H

Hoppy said:


> If you can find a way to set up a pH controller so it actually does maintain a constant level of CO2 in the tank, during the photoperiod only, it could be a good thing. But, the pH in the water doesn't track the ppm of CO2 instantly. There is a lag there too. And, any controller has to allow the pH to vary a little in order to work. Otherwise, it continually hunts - turns on and off every few seconds - which isn't a great idea either. As far as I know most pH controller have a "on" setting and a different "off" setting, to avoid the hunting.
> 
> You can't use a drop checker to track how well the pH controller is working, because of the 2 hour lag in response of the drop checker. It just isn't easy to measure/control CO2 without spending a fortune on equipment.
> 
> It shouldn't take an hour to get the tank up to the desired level of CO2. You can work on the CO2 delivery/diffusing system to get that time period much shorter, but you will always have a big uncertainty in how much CO2 is in the water, unless you buy some very expensive measuring equipment. Even then, you aren't going to be able to pinpoint the ppm of CO2, because it varies widely around the tank, depending on water circulation, plant uptake rates, loss from the water surface, etc.
> 
> Consider reducing the light intensity so the needed ppm of CO2 is low enough to let you safely run it 24 hours a day. Then, the concentration will be a lot more uniform, increasing a bit at night when the plants stop using it, and going back down a bit during the day as the plants start using it.


The Milwaukee controller can be set to have a swing between the on and the off ph so that shouldn't be a problem. My drop check is one of those tiny ones and it seems to read in well under an hour, so that will help. I have reduced surface agitation to reduce loss from the surface. 

I'm doing everything I can do stabilize the CO2 but I just can't seem to get there!


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## Dave-H

Hoppy said:


> It shouldn't take an hour to get the tank up to the desired level of CO2.


At 6 bubbles/second it takes 2 or 3 hours to get the drop checker into a nice green - at least! I first checked for leaks in the system. I have a clear PVC reactor so I can actually see the bubbles being injected into the reactor (which is super cool) and the bubbles coming into the reactor match exactly the bubbles in the bubble counter. So, no apparent leaks in that part of the system.

Inside the reactor I see a swirling mess of bubbles at the top of the clear tube. The vast majority of these bubbles bounce around and around at the top, but only a nominal amount make it out through the bottom. If I look at the filter output, I'll see a tiny CO2 bubble shoot out every 2 or 3 seconds. This suggests to me that the CO2 is dissolving almost completely in the reactor before it's send into the tank. So, no apparent issues with diffusion/dissolving the CO2.

I've moved the DC all around the tank. I am confident the circulation pattern in the tank is slow, steady, and covers the entire tank. When I used a diffuser I was able to follow the bubbles just about everywhere and over a period of 10 minutes even the more dead spots in the tank had bubbles cruising through. So, I am fairly confident that tank circulation is good and the drop checker hasn't' been in a dead spot.

The incredibly helpful Orlando from GLA, who sold me the regulator, is always willing to help out. He asked a series of questions including about surface agitation. I did have a powerhead aimed slightly upward, causing an area of roughness and ripples along the surface. No whitewater or bubbles, but heavy rippling 24 hours a day. He suggested that the surface agitation may be too much so I reduced it massively today. Now the surface has a very gentle swirl to it but for the most part its calm and flat. We'll see how much that helps.


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## Dempsey

Hoppy,

Great info as always. One thing that I still haven't grasped though. I hear run the co2 24/7. Then hear that there is no need for that, just have the co2 kick on a little before lights on. Then here that there is also no need for that, just put the lights and co2 on the same timer. 

Let's pretend that we all have a good idea about lighting and have low to medium lights.

Do co2 fluctuations during lights out effect BBA?

I can understand why folks get confused(as do I). I know that no 2 tanks are the same and it's a matter of trial and error. 

There probably isn't one answer for this but still would be interested in what some experienced folks(like yourself) have to say.


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## Dave-H

Hoppy said:


> Even then, you aren't going to be able to pinpoint the ppm of CO2, because it varies widely around the tank, depending on water circulation, plant uptake rates, loss from the water surface, etc.


Always trust the people who are the most caution and the least dogmatic with their advice, I say


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## wkndracer

*Stuff I've used*

American Marine Pinpoint Controller, down flow reactor, drop checker. Reconstituted RO water 2ppm before adding GH, KH mineral salts back setting parameters, 75g tanks.
The controller has two plugs one for low point active (air or power bubbler (I don't use it)) and high point active (CO2 injection solenoid) with both shutting down at center point so I'm controlling over only half the range. With a 0.4pH range that holds to a 0.2pH range +- the reaction swing on the low side. When I've checked this is very rarely far enough down to activate the low side plug. Been using two units for >yrs. and like them. The bubble rate is beyond counting into the reactors and it drives the pH down within 15 minutes averaged on a 75g tank. The solenoid 'click' can be heard from within the cabinets about 2-3 cycles an evening. 

The down side to this setup is if the solenoid fails or sticks open I'll gas my tanks in short order.
I don't believe you can get much closer than that to a steady ppm using automated equipment without the steady cycle Hoppy referred too.

hope this makes sense


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## Dave-H

Having already experienced a solenoid failure, any reference to a solenoid failure makes me nervous! Thankfully, my CO2 failed in the closed position while I was overseas for 5 weeks and I had to deal with an algae outbreak rather than a bunch of dead fish.

I wonder if I could simply introduce an ph controller as another mechanism to help control this. I would still leave the whole system on a timer. I do like leaving my bubbler on at night, it changes up the circulation in the tank quite a bit which seems to be very good for the plants/fish.


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## wkndracer

The solenoids I have spring closed as do most under failure conditions.


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## Dave-H

How long is the cord that leads to the probe on that ph controller?


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## wkndracer

I think the cable is 10'

Yup just checked
American Marine PINPOINT pH Replacement Probe 10 foot cord Ag-Ag/Cl reference Extended life High supression cable jacket


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## houseofcards

The co2 flux doesn't matter in terms of not having a constant co2 level at night. I think enough folks have successful tanks across a wide variety of conditions without a controller to put this past debate. 

I don't think providing co2 at night is doing anything. You could provide all the co2 you want and if the plants aren't photosyntheising you will still get algae. The co2 flux itself is not causing the algae issues. 

Many, if not most here change a large amount of their water weekly. The result is a huge co2 shift sometimes right in the middle of the day. So whether you use a co2 controller or not you will still get this shift until the co2 adjusts. I've never seen any problems associated with this and this is during daylight hours. So I wouldn't worry about a co2 drop at night or even if it takes the tank a few hours after lights on to get to good levels. If your having issues look to your organic load and lights.


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## Hoppy

Don't forget, the pH probe needs recalibrating periodically.

As far as I know, the drop in CO2 concentration with lights out doesn't lead to a BBA outbreak. It is what happens during the time the lights are on, and how consistent it is from day to day that is important - as far as I know.

When you use a high bubble rate, with an external "Rex" reactor, with a pH controller, you will necessarily get a big overshoot on CO2 concentration. The CO2 collected in the reactor will continue to go into the water until it is depleted, some time after the controller shuts off the CO2. And, again, the water pH changes lag the CO2 concentration changes, further adding to the overshoot.

But if you use a low bubble rate, the controller is mostly just a safety feature, shutting down the CO2 before it gets too high in the tank. A happy medium seems to be desirable?


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## magnosis

For what it's worth, I've recently considered the possibility of using a PH controller together with a Drop Checker, in order to get the best of both worlds and automatically control my CO2.

Turns out this would be either expensive or inaccurate, as explained by Hoppy and others: the DC has a long delay and the controller would end up always under/over shooting the target concentration, unless a gas-permeable membrane is used to reduce the delay in reading PH from the control solution.


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## Dave-H

magnosis said:


> For what it's worth, I've recently considered the possibility of using a PH controller together with a Drop Checker, in order to get the best of both worlds and automatically control my CO2.
> 
> Turns out this would be either expensive or inaccurate, as explained by Hoppy and others: the DC has a long delay and the controller would end up always under/over shooting the target concentration, unless a gas-permeable membrane is used to reduce the delay in reading PH from the control solution.


Certainly it would be more expensive, but it's hard to imagine that it would be less accurate than the information that I already have. I'm dealing with ambiguous parameters, hardly any reference or examples of similar tank settings, and a drop checker that reads an hour or so late. 

Adding a ph controller would at least give me one more reading, inaccurate as it is . Also, I am increasingly convinced that the CO2 systems aren't as rock-solid as advertised. This week I met yet another person who gassed her fish! So, at the very least the ph controller could provide some protection against that.

I understand and appreciate all of this input. 

But, where does this leave me?



With a low bubble count, my dc never gets to a nice green.
With a medium bubble count, my dc is blue when the lights come on and green when they go off.
With a high bubble count, I can start the CO2 hours before the light comes on and it will be green when they do, then I have to shut the CO2 down hours before the light goes off.

So, I'm not able to get a clear understanding of what people are doing, especially with regard to bubble rate, tank size, and timer settings. Clearly every tank is different, but I'm not having any luck stabilizing my CO2.

Orlando's comment that I may have too much surface agitation makes sense. That would mean that I need a high bubble count to offset the outgassing from the surface agitation, and that high bubble count makes the whole thing harder to make stable.

What kind of surface agitation do any of you have? Have you noted that with a rippling surface on the water, much CO2 is lost?


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## Dave-H

UPDATE: With the surface agitation reduced substantially, the drop checker reached a lime green color much earlier than it did yesterday. This is consistent with the idea that the CO2 was outgassing too much from the turbulent surface. Very encouraging to me, because it seems like a lower bubble rate is going to be easier to control overall.

I've reduce the bubble count by about 50 percent and will attempt to configure the timer/bubbles again over the next couple of days.

I am still liking the idea of a ph controller just for safety, but hey I always like a fun gadget!


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## magnosis

Dave-H said:


> it's hard to imagine that it would be less accurate than the information that I already have.


Yes, true. What I meant is controlling when the CO2 valve turns on & off by means of a PH controller -> that is inaccurate. If the probe in the water column, then it's not only measuring CO2, but all the other factors that affect the PH. If the probe is in a drop-checker solution, then it's delayed by an hour or so and will toggle the CO2 valve too late relative to current CO2 levels.

_Apologies, I'm not bringing anything new to the table... back to you now _


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## hbosman

wkndracer said:


> The solenoids I have spring closed as do most under failure conditions.


Mechanical failure, contamination in the plunger area or worn spring can cause it to fail open. If it was electrical failure then yes it would be closed during failure.


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## hbosman

I may seem counter intuitive but, I got more stability in co2 rates by increasing my bubble rate and increasing the surface turbulence as well. The co2 rate is set to where it would be very yellow at the end of the photo period if I didn't have sufficient turbulence at the surface. There's no splashing or anything but the surface movement is obvious. Since there is the drop checker lag, I compare it to ph test kit changes in ph to get an idea how long the co2 level takes to actually change. The drop checker seems to lag more for increases in ph than it does for decreases in ph. In other words, the drop checker changes to almost yellow by the end of the 8 hour co2 period but is still lime green after 16 hours of the co2 being turned off. Using the ph test kit, I can see that ph in the morning should indicate blue.

If this concern with co2 fluctuation is due to BBA or other algae, I think you would be more successful with reducing light intensity. Either raise the fixture or run less bulbs. If you can't get rid of algae with a lime green drop checker, in my opinion, your PAR is too high. If your ferts were wrong, you would see it in the plants.

I used to run 4x39 watt bulbs over a 46 gallon bowfront and always had bba and usually gda. Then I finally was convinced to run 2x39 watts. The gda was gone and the bba slowed down considerably. Now I run the solenoid and one 39 watt bulb one one timer which turns on two hours before the second bulb. Two hours is probably unneccessary but, CO2 is cheap, why not? The two bulbs are on for only 5 hours of the 8 hour photo period. And you know what? I still have to trim stem plants weekly so, no point in running more light than necessary.


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## spdskr

Here is my input as someone who has used a pH controller for the past 5 yrs. Here are some observations during that time:

1. Slowly and carefully determine the stress point for your fish and shrimp. For my tank, at 6.0 the fish head to the surface and the shrimp start swimming. My pH controller is set to turn on the CO2 at 6.2 and turn it off at 6.1.

2. Fine tune the rate of injection to achieve the desired pH level in a relatively short amount of time. I adjust my needle valve several times during the life of my CO2 tank refill so that the gas is not injected for long periods of time (too low rate) or does not overshoot the desired level before the controller can turn it off (too high rate) thus stressing the fauna.

3. Check probe calibration regularly. I use 6 month intervals, but have rarely had to adjust.

4. Diffusion methods can greatly impact the rate of CO2 needed. I have used ceramic diffusers, reactors, and currently the new Atomic diffuser....and each method has required a different CO2 rate to easily keep the pH consistently at 6.1.

As usual, your results may vary. I just thought I would share my relatively long term experience here.


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## Dave-H

spdskr said:


> Fine tune the rate of injection to achieve the desired pH level in a relatively short amount of time. I adjust my needle valve several times during the life of my CO2 tank refill so that the gas is not injected for long periods of time (too low rate) or does not overshoot the desired level before the controller can turn it off (too high rate) thus stressing the fauna.


Is there any lag with the ph controller besides factors like the placement of the probe, etc? I thought that the ph probe was fairly 'instant' in it's readings so overloading the tank with CO2 while waiting for the ph controller to kick in would be rare.


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## hbosman

spdskr said:


> Here is my input as someone who has used a pH controller for the past 5 yrs. Here are some observations during that time:
> 
> 1. Slowly and carefully determine the stress point for your fish and shrimp. For my tank, at 6.0 the fish head to the surface and the shrimp start swimming. My pH controller is set to turn on the CO2 at 6.2 and turn it off at 6.1.
> 
> 2. Fine tune the rate of injection to achieve the desired pH level in a relatively short amount of time. I adjust my needle valve several times during the life of my CO2 tank refill so that the gas is not injected for long periods of time (too low rate) or does not overshoot the desired level before the controller can turn it off (too high rate) thus stressing the fauna.
> 
> 3. Check probe calibration regularly. I use 6 month intervals, but have rarely had to adjust.
> 
> 4. Diffusion methods can greatly impact the rate of CO2 needed. I have used ceramic diffusers, reactors, and currently the new Atomic diffuser....and each method has required a different CO2 rate to easily keep the pH consistently at 6.1.
> 
> As usual, your results may vary. I just thought I would share my relatively long term experience here.


What is the ph of your tank water without CO2? I don't believe that the ph scale is linear so, there will be fluctuation from this as well. In your opinion, does the controller make your setup easier to work with? If so, then its worth it. If you only have to calibrate it once every couple of months that doesn't sound to bad. Have you had to replace the probe yet? If so, that would be something to consider as well.


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## spdskr

Dave-H said:


> Is there any lag with the ph controller besides factors like the placement of the probe, etc? I thought that the ph probe was fairly 'instant' in it's readings so overloading the tank with CO2 while waiting for the ph controller to kick in would be rare.


I have actually experimented with this by turning up my bubble rate so high I could not count it. The pH continued to drop in the tank a couple of tenths after the controller turned it off, and it resulted in stressed fish.

I keep my probe in the opposite corner of the tank from the spray bar and diffuser. I can watch the tiny CO2 bubbles travel the length of the tank, and the plants sway in the current near the probe.


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## spdskr

hbosman said:


> What is the ph of your tank water without CO2? I don't believe that the ph scale is linear so, there will be fluctuation from this as well. In your opinion, does the controller make your setup easier to work with? If so, then its worth it. If you only have to calibrate it once every couple of months that doesn't sound to bad. Have you had to replace the probe yet? If so, that would be something to consider as well.


Degassed tank reads 7.1 in the morning.....higher in the afternoon due to O2 production by plants.

The controller makes my life easier. As long as the pH reads 6.1-6.2 I know I'm in the right zone for the health of my flora and fauna. If my pH is reading higher and the CO2 is running constantly, I know I need to up my bubble rate and/or clean the diffuser.

I only check the calibration about twice per year. I have never replaced the probe.


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## wkndracer

hbosman said:


> Mechanical failure, contamination in the plunger area or worn spring can cause it to fail open. If it was electrical failure then yes it would be closed during failure.


All no doubt true and did say in my post a risk of gassing my fish in short order based on a failure hanging it open.

spdskr's post #22 provided a mirror of what I do here with the exception of the overshoot issue based on what remains in the reactor. Only once in two years on two tanks have I seen fish stress and that was all me. Huge trim cutting back over growth and a WC where I didn't properly verify that the tank dKH value matched the set points. 

KUDOS OP! best controller topic thread I've read to date.


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## Dave-H

spdskr said:


> I have actually experimented with this by turning up my bubble rate so high I could not count it. The pH continued to drop in the tank a couple of tenths after the controller turned it off, and it resulted in stressed fish.
> 
> I keep my probe in the opposite corner of the tank from the spray bar and diffuser. I can watch the tiny CO2 bubbles travel the length of the tank, and the plants sway in the current near the probe.


To what do you attribute this? Are you saying there's lag in the ph reading OR are you saying the ph continues to decrease in the tank after the CO2 shuts off? If the latter, I wonder why that would be?

When my CO2 shuts off there is a mess of swirling bubbles in the reactor, but only for a few minutes max. My RG reactor really does the trick!


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## spdskr

Dave-H said:


> To what do you attribute this? Are you saying there's lag in the ph reading OR are you saying the ph continues to decrease in the tank after the CO2 shuts off? If the latter, I wonder why that would be?
> 
> When my CO2 shuts off there is a mess of swirling bubbles in the reactor, but only for a few minutes max. My RG reactor really does the trick!


I attribute it to suspended CO2 bubbles further dissolving into the water. This has only occured for me at very high bubble rates. I fear your reactor would develop a very large air pocket at these rates if is similar to the one I used.


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## Dave-H

Gotcha. Well, to me it seems much safer and more conservative to keep the bubble rate at the lowest possible rate that will yield reasonable increase in CO2. It doesn't have to happen in 5 minutes, but if it takes hours that is too hard to manage. And I know that my reactor can handle a reasonable rate without continuing to introduce CO2 for hours, so hopefully I won't have the laggy problem.


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## Sharkfood

I've had my set up turn on half an hour before the lights, and shut off an hour prior to the lights since I set my system up on day one. I don't have any BBA as a result of this set up. There isn't a single strand in my tank, and hasn't been since I found the sweet spot on my needle valve some 8 months ago. I still get a small amount of GSA, but it grows very slowly and is easy to mag float off every couple of weeks, or whenever I can see that it is there. Increasing CO2 beyond levels safe for fauna in my grow out tank actually made this algae grow like bonkers.

When I was using my drop checker, It never reverted to blue in the morning. It stayed green all night, though it was lighter at the end of the photoperiod. This leads me to believe that the supposed CO2 swing isn't as pronounced as some might think. It seems to me that CO2 production from the plants at night takes up much of the slack from the CO2 being turned off.


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## spdskr

Dave-H said:


> Gotcha. Well, to me it seems much safer and more conservative to keep the bubble rate at the lowest possible rate that will yield reasonable increase in CO2. It doesn't have to happen in 5 minutes, but if it takes hours that is too hard to manage. And I know that my reactor can handle a reasonable rate without continuing to introduce CO2 for hours, so hopefully I won't have the laggy problem.


Dave,

I'm sure you will do well with a controller. Just remember it will require some fine tuning in the beginning to acheive the proper CO2 level and bubble rate. After that it is relatively worry free.


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## Dave-H

After reading this forum for a while, I'm becoming immediately skeptical of any claim that there is a specific causal action between fluctuating CO2 levels and algae!


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## houseofcards

Dave-H said:


> After reading this forum for a while, I'm becoming immediately skeptical of any claim that there is a specific causal action between fluctuating CO2 levels and algae!


What leads you to believe that?


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## wkndracer

Dave-H said:


> After reading this forum for a while, I'm becoming immediately skeptical of any claim that there is a specific causal action between fluctuating CO2 levels and algae!


LMAO! thanx!
reading for a while / becoming immediately skeptical
love the wording :icon_cool


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## Dave-H

houseofcards said:


> What leads you to believe that?





wkndracer said:


> LMAO! thanx!
> reading for a while / becoming immediately skeptical
> love the wording :icon_cool


Even in this thread there is no consensus! Don't get me wrong, I'm not denying a relationship between CO2 and algae. But there are also apparent relationships between algae and light, ferts, temp, etc.

I have read so many posts about how sudden changes in CO cause algae. I have read so many posts about how they don't cause algae. I have seen massive fluctuations in CO2 as I've tried to stabalze my CO2, hence this thread. 

However, the only algae outbreak I've had in the 6 month history of my aquarium was the time my CO2 solenoid broke in the closed position while I was overseas. A friend of mine noticed that there were 'no bubbles' but didn't know what to do. The cat sitter kept feeding and fertilizing the fish per my schedule, but when I returned home 3 weeks after the CO2 failed to a pretty massive algae situation - not to mention some serious plant issues. With the CO2 back on all day, the algae has steadily reduced.

So, did the fluctuation in the CO2 in the few hours after it failed cause the algae? Or was that the plants stopped growing as much which left extra ferts in the water? Or was it that the plants stopped growing and the algae can invade slow growing plants - my anubias were a mess but the faster growing vesuvius was sort of ok.

So please don't think I'm taking a reductoinist stance on the whole matter of algae and it's relatoinship to CO2 swings. But per my observation it's a complex relationship with tons of factors and little obvious conclusion. 

That said, my observation largely consists of reading this forum and APC so a biologist I am not.


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## Hoppy

The algae attacks that can follow an interruption of the consistent CO2 concentration, day to day to day, will normally not occur until many days later. That makes it much harder to see a cause and effect relationship between CO2 interruptions and algae problems. And, I believe it is the drop in concentration for a day or so that triggers the algae bloom, not just short intervals of low CO2. I could be wrong about this too. Chasing down the causes of specific algae problems gets pretty tiresome, so many of us just give thanks that we don't have the problems, and don't even try to figure out why. And, when we do have the problems, it takes so much energy to get rid of the problems I rarely did much to figure out what my mistake was. I know now that my primary mistake was to use high light. Now that I have corrected that, I rarely even think about algae (I can barely even spell it now :icon_cool)


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## Steve001

Way back in the in about 86 I picked up the book The Optimum Aquarium.
Now specifically in regards to co2 I used instead of the yeast method two containers at first one was filled with Baking soda the other vinegar. Through siphon action I dripped the vinegar very slowly onto the baking soda. That worked for a number years until I purchased a 20lb co2 tank and solenoid switch with needle valve unit sometime in the early 90's. In all that time since I purchased the co2 tank I've let the co2 run continuously never having a bit of trouble. So is a ph controller necessary I don't think so.


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## houseofcards

Dave-H said:


> ...
> However, the only algae outbreak I've had in the 6 month history of my aquarium was the time my CO2 solenoid broke in the closed position while I was overseas. A friend of mine noticed that there were 'no bubbles' but didn't know what to do. The cat sitter kept feeding and fertilizing the fish per my schedule, but when I returned home 3 weeks after the CO2 failed to a pretty massive algae situation - not to mention some serious plant issues. With the CO2 back on all day, the algae has steadily reduced..


Well there's your causal relationship. With diminished co2 levels the plants couldn't uptake and the organic breakdown stayed in the water column, plus you were feeding your fish. Yes more than likely algae will take advantage of that. Again the co2 reduction caused the eventual algae, buy limiting the plants, but it wasn't low co2 causing algae.


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## houseofcards

Hoppy said:


> The algae attacks that can follow an interruption of the consistent CO2 concentration, day to day to day, will normally not occur until many days later. That makes it much harder to see a cause and effect relationship between CO2 interruptions and algae problems. And, I believe it is the drop in concentration for a day or so that triggers the algae bloom, not just short intervals of low CO2. I could be wrong about this too. Chasing down the causes of specific algae problems gets pretty tiresome, so many of us just give thanks that we don't have the problems, and don't even try to figure out why. And, when we do have the problems, it takes so much energy to get rid of the problems I rarely did much to figure out what my mistake was. I know now that my primary mistake was to use high light. Now that I have corrected that, I rarely even think about algae (I can barely even spell it now :icon_cool)


I totally agree. If it was just a short term flux everyone's tank would be overridden with algae from their weekly water changes and that clearly doesn't happen. 

Yes, it does grow tiresome and probably a big reason why many quit the hobby. Personally I found this hobby much more fun when I stopped trying to hit a bullseye with everything and just focused on growing plants, limiting organics and changing water on a regular basis.


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## Dave-H

houseofcards said:


> Well there's your causal relationship. With diminished co2 levels the plants couldn't uptake and the organic breakdown stayed in the water column, plus you were feeding your fish. Yes more than likely algae will take advantage of that. Again the co2 reduction caused the eventual algae, buy limiting the plants, but it wasn't low co2 causing algae.


And again here is some ambiguous language that simultaneous citing 'facts' but also calling this a 'casual relationship'. The language is strong and you make a very specific claim about exactly what caused the CO2 outbreak - so what you initially called a casual relationship. But, are you sure that the reduced CO2 limited the plants which caused the outbreak? Really sure? Any source for that info? 

I'm not saying you are wrong (and I think you are probably right), I'm saying that there is conflicting information all over the place and I have yet to see a solid citation for these facts.

Then there is a post like this with more nuanced language, which seeks to make a conclusion based on the experience and knowledge of a single person but is careful not to offer a scientific fact:



Hoppy said:


> That makes it much harder to see a cause and effect relationship between CO2 interruptions and algae problems. And, I believe it is the drop in concentration for a day or so that triggers the algae bloom, not just short intervals of low CO2. I could be wrong about this too.


Quite different in that it makes a similar claim but specifically addresses the complexity and ambiguity of the problem.

Again, I'm not denying the relationship but I take issue with the sloppy science going around  After all, it wouldn't be very hard to find a bunch of conflicting threads about this topic on the forum, and of course most of them are all very confident in their claims.


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## houseofcards

Dave-H said:


> I'm not saying you are wrong (and I think you are probably right), I'm saying that there is conflicting information all over the place and I have yet to see a solid citation for these facts.


Dave, are we really going to go into the way one talks whether he/she is stating a fact or their belief. I don't think I used the word 'fact' anywhere. What is a fact? I'm telling you what I believe from my vast experience and what I consider success in the hobby. If I told you that I went to a lab and did an experiment that proved this, is that a fact? Will the same 'fact' work in one's home with many different variables that didn't exist in the lab? 

Getting back to the co2. Let me ask you a question. Suppose you setup a tank full of plants and provide rock solid co2 and the tank is crystal clear of any algae. And then you setup another tank with the same parameters (rock solid co2), but only put a single stem of hairgrass in it, do you believe that tank will also be free of algae based on the solid co2.


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## Dave-H

houseofcards said:


> If I told you that I went to a lab and did an experiment that proved this, is that a fact?


If your experiment was properly controlled and repeatable with peer reviewed results, sure we can call that a fact.



houseofcards said:


> Will the same 'fact' work in one's home with many different variables that didn't exist in the lab?


Well that isn't really how such a fact would be expected to work. It may be proven in a lab that a certain outcome will occur based on certain circumstances, but that doesn't mean that you would expect that outcome with 'many different variables that didn't exist in the lab'. 



houseofcards said:


> Suppose you setup a tank full of plants and provide rock solid co2 and the tank is crystal clear of any algae. And then you setup another tank with the same parameters (rock solid co2), but only put a single stem of hairgrass in it, do you believe that tank will also be free of algae based on the solid co2.


I don't know.


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## houseofcards

Dave-H said:


> If your experiment was properly controlled and repeatable with peer reviewed results, sure we can call that a fact.
> 
> Well that isn't really how such a fact would be expected to work. It may be proven in a lab that a certain outcome will occur based on certain circumstances, but that doesn't mean that you would expect that outcome with 'many different variables that didn't exist in the lab'.


Yes I agree. I understand what a scientific fact is, but you prove my point, it's really hard to take a factual experiment and apply it to one's tank since there are so many variables that ruin any control that took place in the lab. 

There usually are too camps with these things the one's that keep trying to find neatly bound answers and they go on and on, testing, changing things, etc and the ones that just understand certain things and makes the hobby IMO more enjoyable. It's like the person that gets Green Water (GW) some refuse to use a UV because they have to find out 'exactly' what's causing it, they need to find 'balance' so they don't see their fish or plants for two months and there there's the other person that uses the UV and their enjoying crystal clear water in a couple of days. I'm with the latter. I don't need to find out everything since I don't think you'll ever know with 100% certainly anyway. I know when I remove organic content as a whole my tank stays more algae free. I also know you don't have to worry about co2 drop at night or for a few hours. I'd trust my knowledge, experience over anyone presenting a scientific 'fact' in a lab controlled environment.


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## Dave-H

houseofcards said:


> I'd trust my knowledge, experience over anyone presenting a scientific 'fact' in a lab controlled environment.


Me, too. And for that matter, so would most other people. 

Unfortunately if everyone is so confident in their conclusions yet those conclusions don't really match we have to look more factual and evidence-based data.


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## houseofcards

Dave-H said:


> Me, too. And for that matter, so would most other people.
> 
> Unfortunately if everyone is so confident in their conclusions yet those conclusions don't really match we have to look more factual and evidence-based data.


Not we, you have to look for it. My conclusions match the end result of what I'm trying to achieve. So 


Sent from my iPhone using Tapatalk


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## Dave-H

can't really respond to that....


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## houseofcards

Dave-H said:


> can't really respond to that....


What I mean is you have to do what you have to do. I really don't think there are that many firm pure scientific facts here. It's called 'The Planted Tank' not the 'The Planted Lab' 

If I drive my car enough times around the same corner and I end up on my neighbors front yard I don't need someone giving my scientific data to know that I need to slow up. Same thing here, if you setup enough tanks you know from your own experimentation what works and what doesn't.


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## wkndracer

houseofcards said:


> What I mean is you have to do what you have to do. I really don't think there are that many firm pure scientific facts here. It's called 'The Planted Tank' not the 'The Planted Lab'
> 
> If I drive my car enough times around the same corner and I end up on my neighbors front yard I don't need someone giving my scientific data to know that I need to slow up. Same thing here, *if you setup enough tanks you know from your own experimentation what works and what doesn't.[/*QUOTE]
> 
> I really liked this post roud:


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## Dave-H

houseofcards said:


> If I drive my car enough times around the same corner and I end up on my neighbors front yard I don't need someone giving my scientific data to know that I need to slow up. Same thing here, if you setup enough tanks you know from your own experimentation what works and what doesn't.


Right. And when all the neighbors start telling you which routes through the neighborhood are best and none of them agree, you become skepitcal of the neighbors input. 

I never said that your own experience weren't of value. I said that was skeptical about claims of 'specific causal action between fluctuating CO2 levels and algae'.


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## houseofcards

Dave-H said:


> Right. And when all the neighbors start telling you which routes through the neighborhood are best and none of them agree, you become skepitcal of the neighbors input.
> 
> I never said that your own experience weren't of value. I said that was skeptical about claims of 'specific causal action between fluctuating CO2 levels and algae'.


Well now your going beyond my statement, but if you want to involve the neighbors I would go with the neighbors who have lived in the 'neighborhood' the longest, LOL.


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## hbosman

Dave-H,

I certainly understand your frustration. When I first started growing plants, I studied and studied an *old* forum that suggested that phosphates were the main cause of algae. I think I spent 6 months researching ways to get rid of phosphates until I found this and some other newer forums with newer information. But on the other hand, someday when we discover the absolute triggers that cause BBA and other algae to occur, that will take away half of the challenge of building and maintaining planted tanks.


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## Dave-H

When you use a ph controller, do you also use a timer or does the CO2 run 24/7??


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## spdskr

Dave-H said:


> When you use a ph controller, do you also use a timer or does the CO2 run 24/7??


I do not use a timer in conjuction with the controller. Also, I notice the controller keeps the solenoid turned off for much of the night since plants are not uptaking CO2 and, therefore, the pH of the water is not climbing as fast as during the day.


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## MarkMc

I use a timer with my controller. No point in wasting CO2 and the fish probably like the break as plants are giving off CO2 at night also. I also use an air stone at night too. As for CO2 climbing too fast during the day I have never seen any sign of stress during this "ramp up" time. I don't believe that the daily CO2 rise and fall during the 24 hour cycle harms my fish in any way. At least it does not _appear_ that is does. I would imagine that a clever ichthyologist could devise an experiment to ascertain whether fish are harmed by daily level changes of CO2.


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## Dave-H

Do you put the controller directly on the timer? It seems like the constant on and off might not be good for it as the ph controllers aren't designed for that.


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## MarkMc

No the controller runs 24/7 but the solenoid is on a timer.


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## Dave-H

But if the solenoid is plugged into the ph controller how can it be plugged into the timer? And if the timer is plugged into the ph controller (so that the solenoid is plugged into the timer) then doesn't the timer lose power when the ph controller wants to turn off the CO2? That screws up the timing because the timer needs power to keep time.

What am I missing??


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## MarkMc

Dave-H said:


> But if the solenoid is plugged into the ph controller how can it be plugged into the timer? And if the timer is plugged into the ph controller (so that the solenoid is plugged into the timer) then doesn't the timer lose power when the ph controller wants to turn off the CO2? That screws up the timing because the timer needs power to keep time.
> 
> What am I missing??


The controller sends a signal to a relay module which in turn needs power from your household outlet (thats where you put the timer) the solenoid is plugged into this relay module. So your controller can energize this "relay module" all it wants but it won't turn on the solenoid unless the timer has let power flow to the "relay module". This way you can look at the controller 24/7 and see what the pH reading is but the solenoid is only powered when the timer allows it.


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## Dave-H

I didn't really get that. 

The ph controller has a switched outlet built into it and whatever you want to control using the ph controller plugs into it. The timer has a switched outlet built into it and whatever you want to control with the timer plugs into it. 

Where would the solenoid be plugged into if not the ph controller itself? What plugs into the timer?


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## mordalphus

plug the timer into the controllers switched outlet, then plug the solenoid into the timer?

Wait, that wouldnt work.


I've only heard of plugging the controller into the timer, so the controller is only on for the photoperiod, but i still hold the belief that its totally unnecessary


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## Dave-H

You are probably right that it's not necessary, but I'm just curious how anyone gets it to work.


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## MarkMc

The Millwaukee controller does not have the receptacle built into the controller. A wire goes from the controller to the "relay module". This wire controls the relay. The "relay module" needs to be powered from your house 120v outlet. When the "relay module" gets power from the controller it basically throws the "switch" inside allowing current to flow from your house outlet though the "relay module" to your solenoid on your CO2 regulator. The set up I'm talking about controls the house outlet so-to-speak with a timer. I don't think you can do it this way with some brands of controllers as they have the solenoid outlet built into the controller.


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## Dave-H

Why do you keep putting relay module in quotes? Are you suggesting that a relay can be put between the timer and the solenoid? Certainly that would work but could a ph controller be wired to control via such a relay?


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## MarkMc

Dave-H said:


> Why do you keep putting relay module in quotes? Are you suggesting that a relay can be put between the timer and the solenoid? Certainly that would work but could a ph controller be wired to control via such a relay?


I'm referring to it that way because I don't recall what Millwaukee calls it and because it _is_ a relay. I'm not suggesting it-it's _how_ I have mine set up. I don't think you can do this with a Pinpoint brand because this "relay" is built into the controller.


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## jcgd

Oh jeez. The solenoid is connected to the relay, the relay is plugged into the timer, the timer plugs into the outlet. The controller is plugged in separately. The timer only lets power go to the relay during the day, and the controller only lets the power through the relay when the timer is "on" and the ph needs to drop.

It only works with the Milwaukee because it only has the one relay. If the relay doesn't have power (because the timer is off) then when the controller tries to turn on the solenoid it wont because the relay isn't energized.

I hope this makes sense. It's hard to get without looking at the Milwaukee setup, but its really quite simple.


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## Dave-H

justincgdick said:


> Oh jeez. The solenoid is connected to the relay, the relay is plugged into the timer, the timer plugs into the outlet. The controller is plugged in separately. The timer only lets power go to the relay during the day, and the controller only lets the power through the relay when the timer is "on" and the ph needs to drop.


Where could I find a device like that?


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## MarkMc

If you buy a Millwaukee pH controller that is what you get. It's how they make theirs.


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## Dave-H

MarkMc said:


> If you buy a Millwaukee pH controller that is what you get. It's how they make theirs.


I'm looking at the specs for this controller and it seems to simply have a switched AC outlet that you plug the solenoid into. What am I missing?


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## spdskr

Dave-H said:


> I'm looking at the specs for this controller and it seems to simply have a switched AC outlet that you plug the solenoid into. What am I missing?


Dave,

That link is somewhat confusing. I use this controller. It comes with a relay that plugs into the wall, or your timer (whatever you prefer) that powers your solenoid. The controller is powered by another plug....you will need two power supplies for the system. If you want to put your system on a timer, plug the relay into the timer, otherwise plug it into the wall. The pH meter will still register even if the relay is unplugged or if the timer is in the off position (as long as you don't have the meter's power source on a timer also). Hope this helps clarify how this system functions.

Duane


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## Dave-H

spdskr said:


> Dave,
> 
> That link is somewhat confusing. I use this controller. It comes with a relay that plugs into the wall, or your timer (whatever you prefer) that powers your solenoid. The controller is powered by another plug....you will need two power supplies for the system. If you want to put your system on a timer, plug the relay into the timer, otherwise plug it into the wall. The pH meter will still register even if the relay is unplugged or if the timer is in the off position (as long as you don't have the meter's power source on a timer also). Hope this helps clarify how this system functions.
> 
> Duane


Duane - Thanks for a clear explanation - now I understand that the controller does, in fact, come with a remote AC relay. That is perfect for my needs!


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## Dave-H

So far the controller seems to be working fine. My ph will settle at about 7.4 with the CO2 off, and setting the controller to bring it to 6.9 appears to keep the drop checker at a light green. Fish seem perfectly fine. I'm not sure if 6.9 is a good ph but I'll keep playing with it.


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## MarkMc

Dave-H said:


> I'm not sure if 6.9 is a good ph but I'll keep playing with it.


The number is irrelevant. It only indicates the amount of CO2 (as confirmed by the drop checker). The question you should be asking is "Do I have enough CO2 or too much or just the right amount?" Forget about "pH".


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## Killavolt

Dave-H said:


> And again here is some ambiguous language that simultaneous citing 'facts' but also calling this a 'casual relationship'. The language is strong and you make a very specific claim about exactly what caused the CO2 outbreak - so what you initially called a casual relationship. But, are you sure that the reduced CO2 limited the plants which caused the outbreak? Really sure? Any source for that info? I'm not saying you are wrong (and I think you are probably right), I'm saying that there is conflicting information all over the place and I have yet to see a solid citation for these facts. Then there is a post like this with more nuanced language, which seeks to make a conclusion based on the experience and knowledge of a single person but is careful not to offer a scientific fact: Quite different in that it makes a similar claim but specifically addresses the complexity and ambiguity of the problem. Again, I'm not denying the relationship but I take issue with the sloppy science going around  After all, it wouldn't be very hard to find a bunch of conflicting threads about this topic on the forum, and of course most of them are all very confident in their claims.


I realize this thread is 5 years old...... but he said CAUSAL .... not casual.


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