How do you know it's 7.8? Do you have a high-range pH test kit? I've never

yes. I do have the high-range pH test kit... (came with the freshwater
test kit).

heard of the water utility adding something other than bicarbonate to
raise
the pH. Why add something else when bicarbonate would do the job?

I don't know what they add. but whatever they add, it doesn't raise the KH
a whole lot.. (tap KH = 2-3.. probably 2.5). But apparently this is not
uncommon.. there was someone else (Massachusetts or Texas, i can't remember)
who had a very similar reading: GH/KH=2-3, pH=7.8-8.0... so...

Also, I think a large water change is the most beneficial thing you can do
right now. I wouldn't hold it off any longer.

this weekend is my big water change weekend.. (I usually do about 25% every
1.5weeks). I'll just do a lot larger than 25%...

linda