I do ~15% water changes every week. So my softies started fizzling out and I checked Nitrate....well over 100. Big problem, but I really thought the WCs would prevent this. So I checked my source water. RO reads 0....freshly mixed salt water reads between 50 and 100. No wonder my water changes aren't working....
I use the Salifert test kit, and Kent Marine Reef Salt. I use food grade blue barrels for everything; the RO is dripped to a darker blue barrel (not sure what kind of plastics we're talking about here), and the salt is mixed in the lighter blue color barrels. I have noticed some algae or mildew growth inside the mixing barrels....I do not keep lids on the barrels. The whole water station is in the back corner of the unfinished part of my basement, temp is around 60F back there.
So, my thoughts on where the nitrate could be coming from in order from most to least likely:
1) The scum on the inside of the barrels is leaching nitrate
2) Kent marine bucket is lying....(it says nitrate free)
3) The barrels are leaching nitrate...also seems unlikely since the RO water barrel is testing clean....but I make this a maybe because the RO barrel is a slightly different plastic than the salt barrels
4) The pump that moves water between the barrels is leaching nitrate
5) The Salifert test is somehow faulty
6) The environment is somehow dumping nitrate into the uncovered barrel....the cat box is also in the unfinished area, not sure how terrible that is....but it is a large (~800sq ft) area, cat box is around the corner....again, seems unlikely since RO is also uncovered but tests clean
So my question for all who read this: what do you think/what's your experience? If it's the scum, whatever it is, what can I do about it? I can't drag these barrels upstairs and scrub them every week. Or does anyone know if Kent Marine is suspect?
TIA.
The Actuary