disconnect co2 at night?

**Lady Hobbs** · 02-08-2013, 12:01 AM

I can only give my experience. I had a 29 gallon, planted with DIY CO2. Each night I would turn on my air pump and airstone. All was fine until one night I forgot to turn the air pump on and when I woke up in the morning I had 14 dead fish. The only fish still living were 3 small angel fish that had their faces literally sticking out of the water.

**funkman262** · 02-08-2013, 12:24 AM

Originally Posted by Lady Hobbs

I can only give my experience. I had a 29 gallon, planted with DIY CO2. Each night I would turn on my air pump and airstone. All was fine until one night I forgot to turn the air pump on and when I woke up in the morning I had 14 dead fish. The only fish still living were 3 small angel fish that had their faces literally sticking out of the water.

I agree that it's not a great idea to continue running the CO2 at night without an airpump. It's important to use a timer so that a simple mistake doesn't wipe out your livestock. Back when I was doing DIY, I didn't have an airpump running at night at first but luckily instead of them all dying, they were just gasping at the surface for air but I still felt pretty bad for them. A timer was immediately purchased and used afterwards. Having pressurized now, I simply have the solenoid on a timer to shut off at night.

**Lady Hobbs** · 02-08-2013, 12:38 AM

Originally Posted by biotsrama

I'll defer to Lady Hobbs for a more detailed response, but "will benefit from" is different from "needed".

Exactly and glad you noticed there is a difference in those two statements. Also, there is a difference in pressured CO2 as well. In most cases, either the CO2 is kept on a timer or an air pump is on a timer. You can't just be depleting oxygen all night without negative effects.

But, yes, all plants "may" benefit from CO2 but it doesn't mean they will fade away and die without it, either.

**Cermet** · 02-08-2013, 11:21 AM

You most certainly can control a passive CO2 system with a timer - the exact same device (electronic manifold) is available that are used for pressurized systems. While the cost isn’t necessarily worth it, I’d say just turn off (use a vent valve) the system at night.

**funkman262** · 02-08-2013, 11:36 AM

Originally Posted by Cermet

You most certainly can control a passive CO2 system with a timer - the exact same device (electronic manifold) is available that are used for pressurized systems. While the cost isn’t necessarily worth it, I’d say just turn off (use a vent valve) the system at night.

Okay, diverting a flow is different. You originally mentioned that running it at night would be a "100% waste of CO2 in your cylinder" and the only way to not "waste" the CO2 is to shut it off completely, so that statement was a bit misleading. I only bring this up because I've seen people in the past asking about using a valve to shut off their DIY CO2 at night, and that would lead to a large (and potentially dangerous) explosion. So while I agree that diverting the CO2 flow is another option, please be more clear in your suggestion for others that may be reading this.

**KingFisher** · 02-08-2013, 11:57 AM

When I used DIY co2 I just left it running all the time. Unless you have a good reactor there is no way that too much will build up in your tank.

**serbusfish** · 02-08-2013, 06:55 PM

OK, first of all the unit I have is rated for tanks of 80 litres max, my tank is around 110 litres, so the tank isnt actually getting a full dosage of co2. Second, I have my filter output just under the surface of the water so it creates surface agitation, surely this is no different to running an airstone? And thirdly I have been checking my fish at 3am for the last few nights with my phone light and they arent gasping or anything, they are just chilling out either near the bottom or in between my plants, so atm it seems my tank is oxygenated enough despite the extra co2 being added.

Btw, something I was wondering, if for example I ever had a powercut to stop the co2 building up could I pull the diffuser out of the water and let the co2 release into the air?

**KingFisher** · 02-08-2013, 10:17 PM

Why don't you just stick an inline valve in the tubing leading from the container to the tank? then you can just close the valve whenever you want. They are very cheap too.

**funkman262** · 02-08-2013, 10:41 PM

Originally Posted by KingFisher

Why don't you just stick an inline valve in the tubing leading from the container to the tank? then you can just close the valve whenever you want. They are very cheap too.

Because these types of systems are not meant to become highly pressurized and closing one can possibly lead to an explosion after enough gas builds up throughout the night.