Being the curious type that I am, I decided to monitor PH levels in my two CO2-enriched tanks yesterday. I know we can't really determing CO2 content based on PH, but that wasn't my goal. I was simply curious to see how much the PH changed throughout the day. Both tanks use tap water, EI, CO2 (from the same 20lb canister complete with manifold and a bubble counter per tank). KH is 3dH and GH is 8-9 dH, for both tanks. CO2 comes on at noon, lights on at 1pm, CO2 off at 8pm, and lights off at 9pm. Here's what I found:
I found it interesting that the PH dropped so quickly after the CO2 came on. Is that an indication of anything useful? It probably depends on circulation of water, where I took the water sample, etc. I think the tank has fairly good water circulation. I use a power filter (Penguin? I think 180GPH) for the 20g and an Eclipse 3 Hood system (250GPH) for the 29g. They both also have a MaxiJet 600 powerhead, dispersing the CO2 via impeller. Both have 65watt CFL, although the 29g Eclipse hood uses a retrofit kit, so the lamp is VERY close to the water surface, maybe 1-2". Too close, I know (I have the algae to prove it!) The entire 29g is going to be replaced soon anyhow. 20g uses a Coralife fixture suspended about 6" above the water, open top on tank.
I guess I'm wondering if I can determine whether I have good CO2 based on this particular PH swing? Plants and fish health are best indicators, I know. If nothing can really be gained by knowing PH, so be it. I still found it an interesting experiment.
Code:
-- PH --
Time 20g 29g Comments
----- --- --- --------
11:00 7.6 7.6
12:00 CO2 On
13:00 6.6 6.8 Lights On
15:00 6.4 6.6
17:00 6.2 6.4
20:00 6.0 6.4 CO2 Off
21:00 Lights Off
23:00 6.8 7.0I found it interesting that the PH dropped so quickly after the CO2 came on. Is that an indication of anything useful? It probably depends on circulation of water, where I took the water sample, etc. I think the tank has fairly good water circulation. I use a power filter (Penguin? I think 180GPH) for the 20g and an Eclipse 3 Hood system (250GPH) for the 29g. They both also have a MaxiJet 600 powerhead, dispersing the CO2 via impeller. Both have 65watt CFL, although the 29g Eclipse hood uses a retrofit kit, so the lamp is VERY close to the water surface, maybe 1-2". Too close, I know (I have the algae to prove it!) The entire 29g is going to be replaced soon anyhow. 20g uses a Coralife fixture suspended about 6" above the water, open top on tank.
I guess I'm wondering if I can determine whether I have good CO2 based on this particular PH swing? Plants and fish health are best indicators, I know. If nothing can really be gained by knowing PH, so be it. I still found it an interesting experiment.