Hey Andy… I have an interesting update…
Firstly, re getting a ‘2nd opinion’—excellent recommendation—thing is, i’m isolated—the folks i interact w/on this topic (& various others) r online—so i mostly interface ‘virtually’ or via telephone, plus, i do plenty of reading/research.
I don’t currently trust the folk at my local pet emporium—recently had an extreme disagreement that was peppered w/disloyalty, & a bit of a back-stab/ghosting… Ergo, it’s online Yodas or a bus ride downtown (not ‘cake’ for me). So i’ve taken matters into my own hands!
As of today (11 May), nitrite & ammonia r back to zero. This result holds from testing yesterday—i’d re-added ~1oz of Dr Tim’s ‘one & only’ on 9 May. Nitrates r 20ppm.
There’s been an unexpected development: teeny weeny, itty bitty snails (see pix. Do u know what species these r?).

& DON’T WORRY: i’m hep to the potential for a ‘population explosion—i read up on the matter following the discovery. My hunch is there were some eggs on recently purchased plants (vs the ones pulled from my 5gal).
I also removed what appeared to be egg masses (would rather neutralize eggs than fully realized creatures). So there r 4 of them (micro snails), & they’re doing a bang-up job of eating algae (which i didn’t want to eliminate specifically for any bottom feeders i might have introduced, but they saved me the trouble!!!).
So, betw. water testing & evaporation, the 10gal water level is minus ~1”; should i just replace (w/conditioned water) or is it time for a partial water change?
Should i continue to keep the tank warm (80F; heater set for 82F)?
Please advise. TY