Here's an update.
Yesterday, I replicated the water I had prepared for my last water change (0.6 gallons) right before I noticed the pH drop to 6 about a week ago:
Tapwater only: baseline 7.8/after 12 hrs pH 7.6
Tapwater treated with Prime and StressCoat: Baseline ph 7.8/12 hrs later ph 7.6
Tapwater treated with Prime and StressCoat + gravel: baseline pH 7.6/12 hrs ph7.6
Tapwater trewated with Prime and StressCoat + marbles: baseline pH 7.6/12 hrs ph 7.6
Will test again after 24 hrs, but so far no big differences seem to be associated with StressCoat or substrate.
I went back to my records from when I first set up the tank (marbles/2 decorations/1 betta) and pH was 6.6 at baseline (day 1) -- I didn't test the tapwater at baseline for comparison. But don't know why my tapwater at least right now is so much higher.
As for the tank, I added about 1/2 tsp. crushed coral to the filter 2 days ago with no pH change detected.
Also, last night did some tank maintenance:
1) rinsed out the sponge filter in dirty tank water
2) added 1.0 mL Stability (I'm paranoid about losing my beneficial bacteria)
3) added a handful of gravel (gravel was getting low in spots; last time I added a layer of gravel to the whole tank pH increased by 0.2 but then went back down then next day). 4) 1 gallon water change with gravel vac in a small area (20%).
This morning ph was up to 6.5. Other water parameters are holding steady (0.25 NH3
). This morning I turkey basted the gunk from the bottom of the filter box. I plan to do some more HOB
-How long should I wait between rinsing out each filter component?
-How often should I clean each filter component? (sponge filter, HOB