Fluctuating Co2

[Steve H.]

I have been working hard at perfecting the balance in my tank. Currently I have been working on the co2. I know my goal here is to get to a stable 30ppm, but when algae occurs due to "fluctuating co2 levels" what does that really mean?

All the time? During the photo period only? High to low? Low to high? Up and down?

 

[ian]

This generally happens during the photoperiod, in any kind of set-up. In low light set ups, to many water changes, causing fluctuating C02 levels can 'exacerbate' black brush algae. The causes of algae will always be light and ammonia, what people seem to forget that there is always some ammonia traces in the tanks, if there wasn't our filter would die. In high tech it can be problems with diffusion, again it will normally end with BBA.

In a low tech set up, the best time to do a water change is at lights out, this gives time for excess C02 to 'gass off'. It remains a little more difficult in a high tech set up. You need to crack the best diffusion method from the beginning. It has been tried and tested that the best thing to do is to have the C02 set on a timer to come on 2 hours before lights on and finish an hour before lights off. Most aquatic plant scientists will agree that the most important part of the photoperiod is the first 2-4 hours, this is where most problems occur as this is where the plants will use most C02, N and P etc etc.

hope this makes some sense.

 

[Steve H.]

Perfect Sense. Thanks Ian!

I guess my question should have been WHEN is the fluctuation they are talking about. Which you answered....during the photo period.

I haven't gone pressurized yet, and I have a yeast set up. I am following Supercoley's thread in the resource center, and have a multiple bottle system to keep the co2 level constant. I have been running an airstone on a timer at night to gas off co2...I am running a bit on the light green to yellow side because I don't have it quite dialed in yet. The air stone is set to turn off 2 hours before the lights come on.

I was concerned that that fluctuation might cause me to have algae problems in the future.

Thanks again!

EDIT: I will reset the timer to turn on 1 hour before lights out for piece of mind

 

[minnnt]

I doubt you would reach the 30ppm with a reactor setup anyway Steve. Always good to aire on the side of caution, but it does allow for a little leeway.

 

[Steve H.]

I doubt you would reach the 30ppm with a reactor setup anyway Steve. Always good to aire on the side of caution, but it does allow for a little leeway.

Thanks Minnt.
The tank is only 5.5 gallons. Like 20ish liters there about. I have 2- 1 litre bottles on it, and I'm getting light green almost yellow in the drop checker...makes me super nervous I'll wake up to some gassed fish one day

 

[bally]

Ian


When you say lights on/out,,,are you talking the tanks lights or the natual light?

If natual light i assume the co2 would need to come on just before dawn and just before twilight

 

[ian]

the fish tank lights, in a natural light room with a tank away from the window, theres not going to be a great deal of active photosynthesis going on.

In a 5.5g you're gonna hit 30ppm with DIY easily. We normally say a tank at 15g and you're maxing out on the DIY side of things, with a few 2l bottles.

Just remember that you need to disperse the C02 well around the tank, and at lights out, raise the filter outlet to cause more water disturbance and there shouldn't really be a problem.

 

[minnnt]

Ah, didn't realise it was only small.

Should work really well.

I ran it on a 70 litre and 88 litre tank, the smaller tank did much better.