# 6 month old DIY CO2 system started siphoning tank water



## Sharper (Oct 26, 2009)

I've had this working perfectly for 6 months now. The standard 2 gallon plastic coke bottle, had tube connector drilled in the lid and sealed with aquarium sealant. The tube went to a glass jelly jar with tin lid, had water in it for a bubble counter. That was also sealed with aquarium sealant. That output tube went to the tank, with an air stone and sat under the intake to my canister filter. When I built this, I read that CO2 breaks down check valves, so they don't work very well. So I didn't see the need to use one. Ugh...now I kind of wish I tried using one anyway.

Thankfully, I was home today when I noticed water running out from under the aquarium stand. But I'll back up to last night when I changed out the yeast recipe (I change it every 2 weeks). When I took the bottle out of the aquarium stand, the tube connector completely came off. The aquarium sealant that was holding it on just fell off. I was baffled, but went ahead and sealed it back to the lid of the bottle. I waited about 4 hours and it felt dry, so I went ahead and made my recipe, hooked it all up and went about my business.

It usually takes about 2-3 hours before I see bubbles. So I was surprised not to see any bubbles this morning when I woke up. I looked at the tube and didn't see any water in it. I decided I'd mess with it later today. Bad mistake.

I walk by and notice water running down the floor, alongside the couch. I found it was coming from the aquarium stand. I opened the stand and saw that the sealant from the glass jar had come undone and the glass jar was completely full of backed-up water. It was a steady stream coming from the tube. Oh and the water that was in the glass jar smelled horrible, like rotten eggs. The plastic coke bottle smelled of the normal yeast smell.

Now I'm baffled as to what caused this to happen. Should I be using a different kind of sealant? Is there a check valve that I can use with CO2?


----------



## anubias6439 (Sep 7, 2010)

4 hours is not alot of time for silicone to cure. Where i work at, we use Dow Corning 3145 clear silicone sealant and it takes a full 24 hours to dry/ cure in the right humidity/ temp


----------



## Duckweed Hunter (Jun 3, 2010)

It takes 24+ hrs (depending on temp) for silicone to dry fully 
and yes there is co2 quality check valves 
heres a link to the one i use lil $$$ for a check but it works
http://www.greenleafaquariums.com/check-valves/brass-check-valve.html


----------



## anubias6439 (Sep 7, 2010)

Duckweed Hunter said:


> It takes 24+ hrs (depending on temp) for silicone to dry fully
> and yes there is co2 quality check valves
> heres a link to the one i use lil $$$ for a check but it works
> http://www.greenleafaquariums.com/check-valves/brass-check-valve.html


+1 for duckweed hunter, i use the same check valve for my pressurized system


----------



## neilshieh (Jun 24, 2010)

you could buy one of those off ebay as well because GLA's shipping will be a killer. it should be something along the lines of rhinox check valve. just search that up, or co2 on ebay. 
i wouldn't use aquarium sealant for the cap. and if you need to apply some kind of sealant to make it airtight than the hole you drilled is too big. mine don't need sealant and still work great. 
you should get a bottle of gorilla glue. safe for all aquarium application after it cures for about 2-4 hours. that stuff is waterproof and airtight. 
as for the water leaking out. that's because with no gas pressure the separator tubes siphon the water out and into the separator and goes from there and leaks all over. consider making a better co2 system.


----------



## Diana K (Dec 20, 2007)

Keep the yeast bottle above the tank, then it takes an even worse problem to siphon the aquarium water UPhill, and it won't overflow. 

I use a separator bottle, like your jam jar, but no water in it. Have not had siphoning problems since. 

I drill the hole for the tubing too small, then the compression holds it. Silicone does not attach well to plastic. Holds for a short time, then gives up.


----------



## timewalker03 (Feb 27, 2007)

I actually use brass fittings for everything in my DIY CO2. I use standard brass nipples that you can buy at a hardware store. I seal the nipple with a small black gasket that is made for sinks that works perfectly. I use it outside the lid and it doesn't break down. I use a pneumatic check valve used for control systems airlines. I bought mine at lowes for 5 or 7 dollars cannot remember. It is brass and works like a charm. I think my total cost to setup enough lids for 6 bottles was about 20 dollars. I will try to post a picture of it as soon as I can.


----------



## BaltimoreGuy (Jan 22, 2010)

You should drill the holes in the tin lid smaller then the tubing so it grips hard on the air line tube. Aquarium sealant doesn't bond well at all to vinyl/rubber.


----------

