Co2 Dilema

[jkc]

Ok, can anyone tell me where im going wrong!?

Day before yesterday I tried to up my CO2 a little as by the chart it looked like I wasnt getting quite 30ppm. A little after I did this the fish started to gasp at the surface so I turned it back down again. I took some of the water from the tank and left it to stand for 48hrs. Yesterday I calibrated the PH probe on the controller and took a reading of the tank water, it read a PH of 7.49. The KH of the tank water is 6.2 degrees.

By these readings I should be able to set the controller so that it keeps the PH at least at 6.8 giving me a CO2 reading of almost 30ppm however I cant seem to get it any lower than about 6.85 (CO2 reading 26ppm)without the fish starting to struggle. Whats going on?

Some possible answers I assume maybe that the tank is plated heavily enough & so the plants are not using the CO2 quickly enough?? not enough flow in the tank???

 

[jkc]

Just another thought, this is a discus tank and therefore the temp is slightly higher meaning less oxygen in the water!?

As no response as yet I can only assume that I must be close to the level of CO2 that I need and there are other factors affecting the readings that I am getting?

 

[themissingelf]

I think you're definitely on the right track when you mention the temp. After reading your first post, my most immediate thought was along the lines of what else may be causing low oxygen.

I seem to recall that Discus are also messy eaters and produce more waste than usual - it could be the your filter bacteria are consuming more oxygen than a low-stocked tanks that usually attain higher CO2 levels.

Personally I'd stick with the level that works for the fish and adjust other parameters, such as light levels and fert dosing to create the balance.