I'm going to update the main post with the info in case anyone comes across this in the future, saves reading the entire thread.
If you get a bacteria bloom in an established shrimp tank - think about O2 in addition to all the other parameters. Lethargic shrimp at the top of the tank and dead shrimp at the bottom in a bloom situation may be starved of O2. Aerate!
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Hi,
So I had what appears to be a self inflicted bacteria bloom overnight, and about 150 adults/Sub adult Cherry Shrimp died out of around 250. My PH was 4.4 down from 7.0. Ammonia is <0.25, Nitrites & Nitrates 0. KH also 0. I can only assume that the deaths were attributed to either the PH or the lack of O2 and not directly to the bacteria bloom? Would any agree/disagree? And why is my PH so low? Is that because the bacteria will be producing loads of CO2? Or has an overnight surge of Ammonia caused a PH drop?
More details below but only for background info, I'm fairly certain of the bacteria bloom cause just unsure as to the mechanics involved.
Normal tank stats are PH of 7, 3GH and 3KH (But I'm constantly fighting KH, I have to monitor it as it reduces quickly).
2 Days ago I did a 30% w/c, and whilst I was at it I turned off the filter and used about 10ml of Hydrogen Peroxide to treat a little BBA. I've done this before no issues. Left the filter off for an hour and turned it back on.
Yesterday I bought some cucumber and added a slice to the tank. I also added 8x Oto's (tank is over a year old so well cycled).
Midnight last night just before the lights went off all was well, everyone happy. 8am this morning 100+ dead shrimp and milky water, staggeringly low PH of 4.4 (maybe even less, it was still dropping on the pen). So I figured that I've messed up by letting the Hydrogen Peroxide into the filter and killed the bacteria, which is the more likely cause, but I did wonder if the cucumber has pesticides which killed shrimp/caused an ammonia spike/caused a bacteria bloom.
I did a 50% water change but the PH was still under 5 (tap water is 8.2 here!) so I'm adding small doses of KH booster, less than 0.1PH/hour, it's now 5.3 and most of the remaining shrimp are happy again. Just a handful sitting around not doing a real much of anything. No Oto deaths.