OK, time for an update as I am in a bit of a holding pattern.
The good news is the white (probably) bacterial cloud is gone. Just vanished. I assume whatever it was eating exhausted, it died.
And the tank smelled awfully for about half a day -- sour, stale laundry type smell (not sulfide, more musty). I did nothing, but it went away later. Dying bacteria?
But something is wrong with the water chemistry. One as mentioned is the PH is still high. I added now two doses of Acid Buffer (Seachem) to try to lower it down into the 7's. I still do not know the cause, but will does and check before I do the first big water change.
Now the bigger problem. I dosed for 3ppm Ammonia. The next day I had barely detectable (I suspect that test was wrong somehow), so I added a bit more, enough collectively to bring it up to 5ppm (but I thought I was bringing it back to 3ppm).
And it zoomed to a bit north of 8ppm (off the scale, but I test now by diluting the tank water with 50% RODI water, then doubling the reading).
I've had people recommend to do a huge water change, but a variety of reasons keep me from doing it, mainly I have to make a lot of water for that and wasn't quite prepared yet expecting my first change to be 30 days or so from now.
So I waited a day (no change, maybe a bit worse), and decided to try adding Ammo Chips, aka Zeolite. I put it into a HOB filter (Aqueon 75) that I had lying around (horrible, horribly noisey filter but it moves a lot of water) to see if I could take the ammonia out without a huge water change.
My goal was to get the Ammonia down around 2ppm or so, and stop -- if it went back up, the Ammonia was being generated by something in the tank (and since nothing live was there, except plants, that was a real problem). If it then stayed the same or started down, I write it off to some kind of ham fisted initial dosing and move on.
I also got a quick circulation test, that was unplanned:
This was API Ammo Chips, and it's VERY dusty. Should have known that but didn't pay attention. The shot above was about 30 seconds after, and this from the other side:
was about 40 seconds later, and shows a pretty uniform coverage, which I'll take as good news that the flow is pretty complete. Not that I intended this test.
After about 4 hours I tested the water again, and it seems definitely lower, maybe 5ppm or so (i.e. a bit darker than 2, doubled). The greens start looking alike, but it sure seemed lower.
The HOB actually wasn't very full of the Zeolite, so I bought some more (Petco this time) and washed it thoroughly in RODI water and added another 1/3 liter or so.
I didn't add more plants yet, waiting for this to work out.
Anyway... it could be the Ammonia is coming from the death of the bacteria bloom (though I've never heard of that), it could be it is soming from the Osmocote+ I have in the substrate -- that I've seen lots and lots of postings on (now that I look for it). But it's high enough it may be killing the plants, so waiting now to see if this band-aide of Zeolite will work.
Oh... I ran out of DI media, which is one reason I'm not overly interested in doing a water change, that and it will take 2 days to make enough water for a real dent in the ammonia levels (and I have only storage for 80 gallons, which might not be enough if I have to do it with pure water changes). Which would mean having the tank half-full, and probably no filters running, for a while - not great either.
And no, I don't want to use tap + prime to keep going, I'm having enough unknowns right now, and our tap water is awful, don't want to introduce more unknowns.
A new filter ordered, I'm going to move my (very low flow) Fluval 306 to this tank, just to add a bit more, primarily surface agitation in the 3rd section that has none now, and put another SunSun on my 45 G tank where I'm surprised the fish are getting any oxygen. The flow is down to a quarter or so what it was new (despite several cleanings). Piece of junk -- I plan to replace it, then take it apart and thoroughly test to see if I can tell the problem. 2 months old!!! And people decry "you are buying bad quality with SunSun" - at least there I'm not paying for high quality. Fluval I did.
Another update when there's news....