I don't really know what the problem is, but since I got a new NO3 test kit, I can give a full report on water quality, exceptin' that it's hard to discriminate between the red colors to determine if it is 50mg/l or 45 or 65.
Evaporated water is replaced with RO water; no water changes.
Amonia is zero and I figure that the tanks are cycled. Two have a mini-filter and one does not.
One is about 2 gallon hex with a betta.
Other two are Petco thingies.
Parameters of the Petco tank are as follows
It has no filter. Amonia is zero so I figure it's cycled. I just added a pinch of Phosphate so that may be on the high side.
ph= 6.5
kh= 6.5
gh= 7
no3= 25mg/l
po4= 5
Hex nano has a filter and also evaporated water is topped off with RO water. I figure this is cycled but has very high nitrates.
amonia = 0
ph= 6.0
kh= 6.0
gh= 5
no3= 50mg/l it's hard to get an accurate reading on this tetra NO3 test.
po4= 5
Tetra test kit says:
"between 25 and 50mg/l conditions still tolerable for fish but partial water change is recommended."
"above 50mg/l ...harmful effects on fish health...25% water change becomes necessary."
Any help is appreciated.

Mark