Fluctuating Co2?

[Rorie]

I have algae issues and i think it could be due to CO2 fluctuation. I tried bumping up my CO2, but in the morning my fish were all lacking oxygen.

It was suggested that i put air stones in during the night to counteract the CO2 the plants give off at night. Is this correct? I thought they gave off oxygen?

My PH fluctuates massively! From 4.2!! to 6.0. I wonder if this is due to the CO2 coming on, then the air stones etc etc. Is this going to create unstable CO2?

From what i understand CO2 needs to be on during the time the lights are on. So how can it be steady if i switch it off at night? Whats the best way to ensure constant CO2 levels?

Thanks

 

[RadaR]

I have algae issues and i think it could be due to CO2 fluctuation. I tried bumping up my CO2, but in the morning my fish were all lacking oxygen.

Might not be low oxygen. Just high CO2.
High CO2 doesnt mean low oxygen. You can have good levels of both which is what we want.
Unless ofcourse you are referring to the high levels of CO2 preventing the haemoglobin in the fishes blood from picking up and maintaining oxygen therefore the fish lacking oxygen around thier tissues.

It was suggested that i put air stones in during the night to counteract the CO2 the plants give off at night. Is this correct? I thought they gave off oxygen?

At night, plants will respire more heavily and thus instead of giving out oxygen as in photosynthesis, they will give off CO2.

My PH fluctuates massively! From 4.2!! to 6.0. I wonder if this is due to the CO2 coming on, then the air stones etc etc. Is this going to create unstable CO2?

It doesn't matter if the CO2 is unstable at night because its dark and so algae cant react either. Unless ofcourse someone has reasons as to otherwise. As for the pH swings, these arent harmful because the carbonic acid is a weak acid. We see no adverse effects from pH fluctuations due to CO2 injection.

From what i understand CO2 needs to be on during the time the lights are on. So how can it be steady if i switch it off at night? Whats the best way to ensure constant CO2 levels?

CO2 comes on 2 hours before lights come on. CO2 shuts off 2 ours before lights turn off.
Solenoids are perfect for this. Alternatively turn the CO2 off at the main valve, not the needle valve.

 

[Rorie]

Thanks for the reply. Yeh, it is all run with solenoids etc, not me standing there with a switch

Previously i had CO2 on before the lights came off as you say. Is there a benefit in having air driven into the tank at night then?

 

[Tizer]

driven how?

 

[RadaR]

Thanks for the reply. Yeh, it is all run with solenoids etc, not me standing there with a switch

Previously i had CO2 on before the lights came off as you say. Is there a benefit in having air driven into the tank at night then?

It makes some folks feel at ease because the surface agitation will drive off CO2, which they fear is going to build up overnight.

 

[ian]

Messing around with C02 all the time by bumping it up and down with result in C02 related algae. Personally i wouldn't bother with an airstone. Some people in the planted community raise there powerheads a little to produce more surface agitation. If you think about it though, if you C02 is being switched off 2 hours before lights out, the remaining C02 should be gone anyways, as the DC would suggest.