CO2 at night - yes or no?

[WyldFya]

It depends....

Fishes need CO2 for respiration, according to the Bohr- and Haldane-Effect in Blood, but the demand could not be measured that easy.

I would never risk my fishes health for some plants...

It is quite enough to keep an aeration... low at day and starting at night, without any artificial CO2...

That isn't enough for many high light setups, and several plants themselves will need more co2 then most tanks are stocked with.

 

[mgamer20o0]

Put the CO2 on the timer with the lights. That way, even if you are changing the light timing, it changes the CO2 timing with the lights as well.

As for cost, CO2 isn't expensive. It costs me 15.00 to refill my 10lb bottle, and I get it refilled about every 9-10 months. Cheap hobby, lol. And my 20lb bottle even less often than that, lol. And it costs 22.00 to refill.

if your going to turn your co2 off at night it should come on a hour or so before the lights come back on. that way there is time for the co2 to build back up.

 

[Lonewolfblue]

if your going to turn your co2 off at night it should come on a hour or so before the lights come back on. that way there is time for the co2 to build back up.

In my experience, not necessary. Even when there's no CO2 being added when the lights come on, there is already a residual amount of CO2 in the water already, equivalent to atmosphere levels due to the tanks surface area. Just like O2 going into and out of the water, so does the CO2 in the air. And it only takes the tank 15-20 minutes at the most to get back up to your optimum levels. So it's not at all necessary to start the CO2 earlier than lights on.

 

[WyldFya]

I don't start my co2 before the lights, because plants don't start photosynthesizing immediately, they take a little while. I noticed no difference between co2 before, and co2 only when lights were on.

 

[Andrewtfw]

I think one must also consider the fish bio load in the tank. The risk of suffocation at night increases when you have a large bio-load of plants respiring co2 and fish doing the same.

 

[Lonewolfblue]

I think one must also consider the fish bio load in the tank. The risk of suffocation at night increases when you have a large bio-load of plants respiring co2 and fish doing the same.

If you have adaquate aeration at night, then no problems. CO2 does not displace O2. So as long as you have adaquate O2 levels, even with high CO2 levels, there won't be any problems. I always have surface aggitation 24/7 on my planted tanks (1 powerhead aimed at the surface). It's easily doable with pressurized CO2.