Happy 420
@Rexer Sorry to hear you're having so many problems with these deficiencies. Sounds like you've got a great crew helping you nail it down
. My only experience with MC is watching hydro grower after hydro grower ditch it for one reason or another.
I also had a very recent conversation with a local shop owner regarding water filters and RO systems. He seems to swear by RO water causing wild PH fluctuation and something about how RO filters essentially deionize the water, causing Cal/Mg to bind to the water making less available to your plants. This would also cause rises in your EC while still seeing underfed plants or even possible Cal/Mg deficiencies. I'm sure there are a lot of variables and information he is missing here and if i had the time, i would definitely research the theory a little more. But it's definitely something to think about.
Our family and pets drink RO every single day with no issues. I have also done 2 grows using it with no issues either. But this current grow is using a simple 2 stage filter, and maybe there is a little placebo affect happening here, but i swear we have never had an easier time keeping a stable PH.
Have you tested the effects of the perlite you are using on PH? If i remember correctly, you said it was clouding up your water in the beginning. I would think if it can mix that thoroughly to discolor the water, maybe the perlite buckets are throwing the system off?
Sorry for the rambling, just brainstorming here. Wishing you the best of luck man!