Regulating a DIY CO2 supply.

[Alshain]

I know its more difficult to regulate DIY than a pressurized system, but has anyone ever used a gang valve to control the amount of CO2 entering the tank? Will that work?

[An t-iasg]

I have never tried to regulate the CO2 coming from my Hagen (yeast) system. The problem with controlling the amount of CO2 coming from a DIY system is that the yeast mixture makes CO2 constantly (until it expires, of course) and if you don't let this CO2 escape, you risk a rupture of your bottle or along the lines somewhere. If you try to control the escape of the CO2, the pressure may build up in the system somewhere until it bursts. The resulting "explosion" would blast a gooey mess (the contents of your bottle) all over the room! It's hard to tell if the burst would be a rather small fizzle or a big enough explosion to hurt you or break something in the room. For this reason, I wouldn't try to regulate the CO2.

[Alshain]

Well, thats why I mentioned a gang valve. The input from the yeast system goes into a dual gang valve and one side is connected to your reactor/diffuser. The other side is open to atmosphere. With carefull control you could bleed off enough CO2 to relieve pressure and still only get the CO2 you need in the tank.

Anyway, this was just an idea. I'm not sure that you would NEED a way of regulating a yeast CO2 system if you get a good yeast mix, it shouldn't produce too much anyway right?

[src]

It's hard to imagine a DIY system overpowering most tanks, unless you are using too big a generator for your tank (i.e. 1G DIY for a 5G tank). I'm sure there are very few people who's DIY system is overproducing CO2. If yours is, use a smaller batch in a smaller bottle.

The need for a regulator in a tank system is to prevent a "tank dump", where you dump the contents of our CO2 tank all at once. A DIY system isn't a static pressurized source - it's a constantly generated source, and thus there isn't any opportunity to suddenly dump a ton of CO2 into your tank. You won't see a sudden lethal jump from 30 to 100+ppm from DIY.

[An t-iasg]

True, a "tank dump" of CO2 is very unlikely with a DIY system. I know how a gang valve regulates air; I have one on my airpump, and I think it's still too risky to put on a DIY system. There would be such a fine line between adjusting the gang valve for the correct mix of CO2 and air when you really don't know the amount or pressure of the CO2 coming from your bottle. You could end up inadvertently bleeding off your CO2 or holding it back just a little too much and risk a burst.

[czcz]

One way to regulate it is to use a bell diffusor, since excess CO2 will overflow out. Not efficient, but works.

I think it's best to just shoot for levels above your target, then stagger the bottles to keep you there. If the fish aren't gasping, it's not too much CO2.

[malkore]

the problem I see with the gang valve idea, is DIY doesn't produce much pressure, so I see it easily taking the path of least resistance, which is gonna be the open valve with no tubing that's submerged.
it may work though.

however, I don't see a reason to regulate DIY. Often you're lucky to get consistently good/adequate CO2 rates to begin with. If you over 10-15ppm, big deal, the fish won't care, and the algae will hate it.