Bingo...I started think that same thing (my r/o membrane is zapped and re-releasing shit back into the water).....I've never used coco specific nutes, I don't even use cannabis specific nutes in coco. I use control release fertilizers, and only have to adjust the water ph and add 5ml/gal cal-mag. It doesn't get much easier.
As far as your RO water, I'm guessing your filters have failed, and if you have some sort of real nasty element in your water (which in your tap is below any level for concern) but with a failed filter it's being released back into your RO output at a much higher concentration. Until you get your filters changed I'd recommend just using your tap water.
I've mentioned here on RIU several times about a mutual grow with a friend using ONLY Maxibloom in a DWC...friggin plant is a monster!!!!I use maxi bloom no issues at all all you need is maxi bloom.
Bro we are so freaking amp'd over the simplicity of coco....I've successfully been farming with GH Floranova Grow & Bloom with a dose of CalMag as needed - stunning results from the first time in coco has me hooked
From what I gather, they are no longer making the "soil & coco" formula. Only one label/formula now.Been using CNS17 bloom lately with decent results. I can't find the coco specific bottles in gallons, so I just bought the regular and add a bit of calmag every watering.