DIY CO2

[Lily'sDad]

I'm new here but I've noticed a number of people recommending pop bottle CO2. So fwiw I want to share my experiences with it.
I had a planted tank with Amazon Sword and Val. The Sword was huge and took up at least half of a 75 gal. It was doing fine but I can't leave well enough alone. I set up a Coke bottle fermenter and plumbed it so the CO2 was injected into the inlet of the Fluval filter. This worked fine for awhile and there was a noticeable increase in growth. Especially when the bottle was freshly charged. Then, I still don't know why, but the filter inlet created a vacuum and some of the solution from the pop bottle was sucked into the tank. Oh! Bad! Very bad!!! The yeast grew very quickly and took over the tank making white thready growth and a horrid smell. I saved some of the fish but the setup was ruined.
I had to start over, clean it out and begin again. After awhile, I set the bottle back up. Yes! I'm that stupid. Only this time I set it up so that the CO2 inlet wasn't in the filter. Rather it was injected into the water below the filter inlet and rose into the syphon tube. Cool! Worked great! Until the pop bottle got knocked over. Same thing, yeast in the tank.
I won't use homemade CO2 fermenters anymore. There's just too much that can go wrong with them.

[Squawkbert]

A couple of large water changes will cure the ills of fermenter broth getting into the tank.

Strap fermenter to something, use a gas trap, underfill bottle a bit more...

My experience in graphic detail:here (http://www.aquariacentral.com/forums/showthread.php?t=91838)

[Lily'sDad]

My experience has been that as long as there is an inoculant of yeast, it will grow until it dies off. As your link said, you have to remove all water and clean it out. Big job!

[legendaryfrog]

I wouldnt bother with DIY co2 for a big tank like that in the first place. the long term cost is pretty high.

Have you ever looked into a pressurized system?

[Lily'sDad]

I just talked to a friend at church who sells/ delivers bottled gas. Asked if he could find me a used bottle and regulater.

[Squawkbert]

If you score those components, you'll still need a (good) needle valve, tubing & plan for dissolving the CO2 into your water.

[Lily'sDad]

I've had good luck with the bubbles going into the filter inlet. The Fluval does a good job of mashing up the bubbles.

[smyke]

I had some of the yeast sucked into the tank just recently. It wasnt a whole lot but definitely caused the fungus to grow on the glass and everything else. I did about 5 60% water changes over the next couple days and it was gone. its been almost 2 weeks now and so far so good.

[jmhart]

To prevent this I use a gas separator: Gatorade bottle half filled with mild bleach solution(to kill any yeast that passes from the co2 bottles to gas separator). Never had a problem.

[smyke]

after I had my problem, JM suggested the gas separator and I have had no problems since then.

[Mgamer20o0]

lol good old bubble counters..... very often worth it. on a 75 gal tank i wouldnt bother with diy co2. really to get to the levels you need you would prob have to use 3-4 bottles it wont be stable.....