It didn't change much at all. But I did go get some crushed coral. It wouldn't fit in my filter so I just mixed it with my current substrate and bam. Ph problem fixed!!
Bam problem not fixed, problem masked...
You still have no idea why your pH shifted so much if it did not off gas in the 24 hour test fresh suggested...
You may have achieved the desired level but for how long?If it bounces around you could be doing more harm then good till properly diagnosed and corrected?
I was going to suggest the crushed coral after the test said it was just your water off gassing, but now? Maybe you know why your pH was so low but I don't...
It takes some pretty strong chemicals to alter water parameters....
Don't get me wrong I make water as I please owning a 150GPD ro/di unit ,but it is often best to understand as much as possible before making corrections...
You should toss some of your cycled media from old tank in the new to help seed it,Plecos are a rough choice to cycle fish in with!
How water do you change when you say partial water change?
Do you own a test kit as these are a MUST have for fish in cycles..
If yes use it now....