My thought was a bacterial bloom as well. You have a strain of something that likes to eat whatever is in your tap water. Probably not a problem but it could also be some really fine silt (sand bottom tank?). You could buy some water clarifyer and see if that helps. After bottled bacteria (which it seems you already added) it would be the next thing I would try on one of my tanks.I read through some old threads on this, but I'm not really satisfied with the explanations I found.
I have a low tech 54 gallon that's been running for 7 months with medium stock rate, medium plant density, and a Marineland 220 canister filter. I've noticed that after water changes, a white-ish haze develops that lasts a few hours then clears up. The fish don't seem bothered at all, and I've never had any losses. My water is usually crystal clear. I never service my filter on the same day I do water changes, and I rarely do more than a 15-20% water change. I do WCs every couple weeks. I serviced the filter about a week ago and rinsed everything in tank water.
I don't test my parameters religiously, but everything is normal today:
Nitrites and Ammonia: 0
Nitrates: 10? 20? Orange on the API Freshwater Master Kit
pH: 7.6 (it's always this high, just is what it is - I live on Karst limestone)
Today, I just topped off, no WC, with an addition of only a couple gallons, and within a couple hours, the haze showed up. The kicker is, I also topped off my 5 gallon planted betta (+1 baby platy and a snail) tank with the same batch of treated tap water, and that tank did not develop a haze. Today I used Jungle Start Right just to use up a small bottle, but I've had this same result with Prime.
So am I doing something wrong here? Can anyone shed any light on why one tank reacts differently to the same water? I gather that temporary white hazes are usually bacteria blooms, so does that mean that something is amiss with my bacterial colonies? Is this bad for my fishies, even though they seem unfazed?
As I've been typing this, the water has mostly cleared up.
Thanks in advance for your input!