And this metricide eliminates the need for injecting CO2 then? Interesting, will have to read up on it. I thought the whole point of CO2 is that most plants aren't meant to be submersed 100% of the time. I thought you couldn't compensate for that with more fertilizer or plant foods..
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I guess what I'm not explaining very well is that what has me stumped is not that "it takes a lot of CO2." I understand I'm losing CO2 due to the sump. What has me stumped is that no amount of CO2 makes ANY difference.
Let me explain - in the past, although it took a lot of CO2 to lower pH, the CO2 DID lower the pH, there was a measurable difference between CO2 on and CO2 off. Currently what is happening is that it doesn't matter how much I add, it makes no difference to the pH. The equipment hasn't changed (same reactor same tank, just a different point in time). I was just trying to seek out potential causes for this change and thought maybe it was because the carbonate hardness seems inexplicably high as well.
I've even reduced the surface agitation quite significantly by removing the Tunze and it made no difference.
Unless I have a cylinder of just raw air and not CO2 maybe, but it was filled from the same fire extinguisher refill place I've used for the past decade so I have no reason to suspect that this is the cause.
PS. Cale I'm sending you a PM..