Depends on your water source also db. You can only do so much. Even when I was dripping 250 gallon per day of only pure ro in the system is was still only able to get it around 100 . Amazon river water is around 10-30uS not possible to maintain in an aquarium
Also db ill tell you a story of when I first started testing with Tds and conductivity meters. My first reading was a Tds over 1000. My rays didn't breed and cichlids would all get hole In head.
Here's some steps
-prevent evaporation
-remove water and fill old fashion way
- instal reverse osmosis
-lighten the biological loads waste contributes to solids
-instal the best particulate filter possible something that can polish your water effectively very low micron at a high rate
I was but my probe went bad last year and I have not replaced it yet. When it was working it was reading 175 - 250. The probe would not calibrate to the #'s on the calibration solution.
So most of us have decent luck keeping/breeding because we have good tap water, big waterchanges, and good filtration.... In turn keeps conductivity levels down fairly low
Looks like you finally found your problem DB. Im very happy for you, hopefully you can get this under control and rely start enjoying the hobby!!