Okay, this one has me searching for an explanation. My tank is going through some changes (imagine that
). Here's the story...
I recently added two nice pieces of driftwood, and removed one smallish, highly creviced piece of driftwood, that had become my loach/nocturnal fish 'motel'. Within days, I noticed increased plant growth on glosso and stellatus, but I also seemed to have significant crypt die-off (wendtii and balansae). The wendtii was "bulldozed" back 2-4 inches for the dw, but the balansae wasn't touched. Anyway, thinking that that smallish driftwood was the key to my tank long being 'different' and assuming it had been leaching acids into my tank (which I had discovered 'related' driftwood did in the past!), I did a 3x 50% WC. One right after the other. I added 1/2 dose of Prime during the first WC, and a full dose of Prime during the last refill.
To add to this, I finally got fed up with my Milwaukee all-in-one, and suspecting it was a regulator issue, I went to a welding shop and got a replacement (yes, they did have to custom make an oxygen to "pipe" thread adapter for me...after an unsuccessful trip to HD to seek one). Well, the new regulator worked like a charm...for 3 hours! Then whoosh, something inside gave out. So, no CO2 going into the tank since before the WC. To compensate for this, I added 25 ml of Excel last night.
So, this morning upon waking, I find a slew of fish gasping at the top of the water. My rummynose have almost no color, the cardinals are looking pale. In addition, the cory's are looking listless. What gives?? My spraybar is angled upward, like always to create some surface movement. Then I note that my SMS122 shows a pH of 6.9! It was 6.7 before the WCs. It showed 7.2 after the WCs. So, out with the test kits! My KH=8, NH4=0, NO2=0, and pH=7.
With a KH=8, no injected CO2 and an 80+% WC, my pH should be around 7.8! Maybe all the CO2 hasn't outgassed yet, but the pH should be above 6.9! And what's up with the fish gasping? During a regular WC with my pH typically around 6.4-6.5, I hardly ever see this problem (though I have once in a while).
Anybody got any ideas? Stumped...