Thanks for the thoughts guys.. I don't have any limestone though. Yeah I did some more reading and came to the conclusions that neither the substrate or driftwood could explain the high pH. The only thing I can think of is that this tank kind of dropped off my radar for a while and I didn't do waterchanges for a long time (several months) and in the meantime just topped up, so maybe it's been building up for a while.
I kind of kicked my own butt into gear over this over the holidays and have been vaccuuming and waterchanging like crazy so I would have thought by now the pH would be closer to the tap water going in, but maybe I have more to go.
Is filtering through peat a good idea?
I'd take you up on the trade if you like, I don't have a pH controller but I do use a Milwaukee pH meter for checking pH. It's probably due for a probe replacement but I don't think it's shot seeing as I get plausible (and different) readings on other things so I think the >8 pH is probably correct.
So being without a controller, I just set the bubble rate to be reasonably steady and I watch what it does to the pH. When I first started injecting CO2 I found some chart online that matched target pH's to KH readings so I would just find a bubble rate that got me into that ballpark. I'd just increase the bubble rate right now except that I don't see any evidence it's pulling the pH down so I'm not sure what to do.
The tank particulars - 65g, has a sump, bioball tower. The CO2 is from a 20lb cylinder, the regulator and bubble counter are Milwaukee brand, and the reactor is a Red Sea cyclone mixer (
this thing) .. I want to eventually upgrade to one of
these.
Lights are 4x39w t5's, although I have 2 of them turned off for the moment until I get things straightened out.
I did have a Tunze 6055 for extra circulation in there but I've taken it off for now too in case the agitation was causing the CO2 to gas off out of the water too early. Although it hasn't made much of a difference so that's probably not it. I have a bunch of small tetras though and they seem more comfortable without that extra flow so I might keep it off anyhow. It was there for the loaches in there originally but they don't seem to be minding the lessened flow either.