# check valve necessary diy co2?



## phanizzle (Jun 28, 2007)

is a check valve necessary for a diy co2 setup? i just stopped using my hagen co2 system container because it was too small and made a 2L setup still using the hagen ladder. i was wondering if a check valve is necessary? and where would i place the check valve? in the cap or between the tank and bottle?


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## RoyalFizbin (Mar 7, 2006)

It is always recomended to use one. It's there to prevent your tank from siphoning out onto your floor through the co2 hose. Whether you use diy or presureized co2, there is still that chance that a tube could become detached and alow your tank to drain out. Some check valves require greater presure than others. I hope somebody else can recomend you a specific model or brand. 

I personaly have stoped using them on my diy co2 setup. I don't like how it slows down my co2 at the end when the pressure isn't very strong. It's a risk im willing to accept.


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## dekstr (Oct 23, 2007)

A chelve valve is just an extra precaution. It's not neccessary but highly recommended. Like you will still be able to do DIY co2, but just in case so tank water or yeast/sugar water don't mix, or tank water back syphons onto the ground.

You put a check valve in between the bottle and tank, so cut the line and connect it in between.

Some things to take note of:
1. Make sure you get a quality check valve, last thing you want is a wonky check valve. 
2. Also, make sure it's pointed the right way as you don't want any exploding pop bottles. It nearly happened to me before, I hooked up my DIY co2, was wondering where the co2 was. Turns out check valve was on backwards, the three 2l bottles nearly exploded. You can check by blowing into one end. If air passes through, that's the direction co2 should flow, from bottle to tank, not other way around!
3. Another thing is sometimes when you disconnect a checkvalve water back syphons, gushing water out onto the room, so be careful of that too.

I have used it on some set-ups and not on others. It really depends, it is highyl recommended though.

Oh yeah, if you are actively diffusing the CO2 (such as through a powerhead or impeller), I highly recommend one. Why? Sometimes the suction power of the active diffuser is so strong it out performs the amount of co2 that is produced. What ensues w/o a checkvalve is that all the air in the bottle is sucked out, then all that yeast/sugar water is sucked into the tank. Not a pretty sight. Fish will die, the yeast doesn't go away forming gunk all over your tank.


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## loachlady5 (Dec 9, 2007)

Definitely use one. Cheap and easy precaution.


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## Bugman (Jan 7, 2008)

From one who has experienced coming home to half the aquarium water soaked into the carpet.

USE A CHECK VALVE!!!!

You may never need it but if you do.......................................


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## jaidexl (Sep 18, 2006)

If you hook up the recharged bottles while the water is still hot, you might want a check valve, or else tank water will be pulled into the bottle as the yeast mix cools and contracts.

I don't use them on DIY anymore though, I either let the bottle cool before hooking it up or I open the bottle in the morning and pour a few inches back out of it, tank water doesn't kill the yeast (you have to make sure to lift the cap/tubing end above the tank right after opening the bottle or it'll siphon onto the floor and splash all over the walls and your pants as you flail around in horror).


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## jaidexl (Sep 18, 2006)

dekstr said:


> Sometimes the suction power of the active diffuser is so strong it out performs the amount of co2 that is produced. What ensues w/o a checkvalve is that all the air in the bottle is sucked out, then all that yeast/sugar water is sucked into the tank. Not a pretty sight. Fish will die, the yeast doesn't go away forming gunk all over your tank.


Only a gas separator can [may] avoid that, the check valve would have to be turned the wrong way to help. Best thing to do is just not put a yeast feed into a power head or canister line.


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## mahoro (Dec 18, 2007)

you can always connect diy co2 to a diy bubble counter... almost impossible to suck out water from it.. plus if your diy yeast bottle tip over or something, it goes to the bubble counter first, and not your tank...


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## Sticky230 (Mar 30, 2008)

what about a gang valve instead of check since the low pressure may cause problems?


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## John7429 (Jan 11, 2008)

I use a valve with all air tubes going to the tank...


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## eyebeatbadgers (Aug 6, 2007)

Sticky230 said:


> what about a gang valve instead of check since the low pressure may cause problems?


I believe the fluids from both ends could still travel either way through the gang valve.

The only problem with check valves in DIY applications, is that the low pressure can cause "spurts" of Co2 to enter the tank, instead of a nice steady flow. The spurts can be regulated via using an airstone, such as limewood, but if you are using a ladder type diffuser, spurts of CO2 could cause inefficient diffusion. I personally recommend using said limewood airstone at the bottom of the tank under the output of your filter or a powerhead for the best way to get the gas spread around the tank.

HTH


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## EdTheEdge (Jan 25, 2007)

Hmmmm, how does back siphoned tank water end up on the floor in a DIY setup? It is a closed system afterall.... isn't it? The only way that could happen is if you have a bad connection/leak in the first place. Other wise tank water would just siphon into the DIY mixture/bottle and eventually end up back in the tank. Which can be DEADLY to your fish.

I have 3 DIY setups going now for about 8 - 10 years. I use a check valve on one setup because it is below my tank. The other two I keep on a shelf above the tanks which helps to prevent back siphoning.


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## DiscusIt'sWhats4DinneR (Apr 25, 2008)

EdTheEdge said:


> I have 3 DIY setups going now for about 8 - 10 years. I use a check valve on one setup because it is below my tank. The other two I keep on a shelf above the tanks which helps to prevent back siphoning.


 
like he said, if the bottle is below the level tank, use a check valve.
otherwise, you can go without. 

the line cant siphon while the bottle is connected because of the co2 pressure.


but when you unhook it to refill it, and you go to refill the mixture, the few minutes that you are away could be when the tube starts siphoning water onto the floor... 

if you have "spurts" of co2 from the gas building pressure in the check valve and it causes problems with your hagen ladder then i would just not use a check valve, BUT when refilling the mixture be extra carefull to remember always to grab the bottlecap end of the line and drape it over the tank somehow, just lay the tube over the top of tank. that way it cant start syphon.


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