[Delphinus]

Thanks for the thoughts.

The important question is, what's causing the precipitation? I.e., if it was a pH issue (or whatever), what's causing the pH spike? Ultimately, it's either something in the water, or it's something in the salt. Or it's an artifact of the mixing process itself. The behaviour is EXACTLY like what was reported with the bad batches of IO last year. Ironically I never had this problem with IO (and I had been using IO for many many years up until now). I thought I'd better pose the question here to see if anyone else is noticing something, or if someone sees something in my methods that obviously not optimal (or something like that).

I haven't checked the temp of the mixing water but the heater is set to 26 (high 70's in F). I'll throw a thermometer in there and see what it's really at. FWIW, it feels the same as tank water to me, it's not noticeably warmer (like bathtub temperature or something like that).

It's a big heater though, probably way overkill for a 30g mixing bucket, but it was just one I had lying around. Offhand I'm not sure of the exact wattage but it won't be smaller than 150W.