CO2 Recommendations for 250gallon system

[Fenrir]

I am running a medium planted 210 gallon tank with a 40gallon breeder sump with 2 48" Fluval 3.0's. What would you recommend for CO2 bubble rate? The CO2 gets pumped into the Sump.

[Mmiller2001]

Bubble rate is irrelevant. You want to calculate pH drop from degassed to peak gassed. So you would take a pH about 30 minutes before lights on, then take a pH about mid way through your photoperiod. You want a 1 to 1.5 pH drop. That will be pretty close to 30ppm CO². 

You can also calculate CO² by testing KH and pH and use a CO² chart, however, pH drop is more accurate.

[Tinyfellows]

@Mmiller2001would c02 be higher at a one point drop if you have a higher kh than at 0 kh like you run? 

[Mmiller2001]

No, so if you had a 10dKH tank, and say a 9pH degassed, you would want a 7.5 to 8pH while injecting.

Once you observe a 1pH drop, keep an eye on your fish. You can keep pushing a bite more but if they congregate at the surface, then back down just a smidge and you're there.

Edited August 26, 2021 by Mmiller2001