I haven't done the pH in/out test with plain soil in a pot yet. I think I will do that soon.

Just fed my 'test' plant. It's in a 10qt paint bucket for the first two weeks of flower, then gets transplanted into a proper 12" 3-gallon pot. This plant has been in the bucket 5 days. I fed it a quart of RO+1/4 tsp CalMagPlus pHed to 7.0 (clumsy with the pH adjust) and then a quart of RO+1/4 tsp CalMagPlus+ 1/4 tsp TigerBloom+ 1/4 tsp BigBloom that was pHed to 6.9. Got 6oz+ of runoff at pH 6.2. That seems bad.

I'm kicking myself for cheaping out on the pH pen and not getting one with better accuracy.

This is with never-used soil with the lime and perlite added. Now, the soil bag sat in my garage for a few weeks, and who knows how long outside at the garden center. The perlite has some nutirents added to it (MiracleGrow is all I can find) Dunno if that matters.

Thanks for your help!