[anglfish]

Thanks you guys for your input on this...
and..

I KNEW IT!

so it IS the water. Well that kinda is a release as now at least I know what I can do to fix this. I just have a 24 gallon so I don't think the $25 month plan will work out for me. But I make sure to use only RO water treated with Ozone that has very little TDS.
Will do a big water change today and then another one in a week and see whether this helps. the diatom should "starve" out after two weeks, given I don't everfeed. right?
any other short term solution I can use until then?

Todd, where is the Alternate Water Store?

Thanks again!