Yeah that's my biggest beaf with mega crop they keep adding more nitrogen when it's not needed. When I've done the tap/RO thing I just mixed up 50-100 ppm. My tap is really high 350+ppm loaded with calcium carbonate and really alkalinity I had to cut my tap 3:1 ro:tap to get me <100ppm. So I think I know you well enough do you even know your tap water's ppm? Can you get a water report online? I couldn't just tested mine with at home test strips and a EC meter. OK never mind just read your latest message it has taken me a minute to make this message
Gypsum pretty easy to find you can get small bags on Amazon this is what I started with
Amazon.com : Down To Earth All Natural Fertilizers Organic Solution Grade Gypsum Calcium Sulfate - Professional Grade Gypsum Powder 325 mesh for Liquid, Drip or Spray Applications, 1 lb : Patio, Lawn & Garden
a.co
I get this from BAS it's a much better deal last a long time I split it up into mason jars after opening bag. After finding you the link they used to have smaller bags at BAS they only have 50lbs now it's cheap but pita to store
Enrich your soil with Diamond K Gypsum, the premium 97 solution grade for optimal plant growth. Available in versatile 3lb, 10lb, and 50lb sizes to cater to your specific gardening needs. Enhance soil structure and plant nutrition with our pure, high-quality gypsum.
buildasoil.com
So I just remembered I did this the most recent time same deal just on amazon smaller bags.
Amazon.com : The Seed Supply 5 Pounds Diamond K Gypsum Soluble Grade Fertilizer Powder : Patio, Lawn & Garden
a.co
The main thing is that's its solution grade. I'm pretty sure this is my favorite way to do it cause it doesn't add any nitrogen. Tap was ok just little pain always having a bucket of tap ready to mix cause I would bubble it 24hr to make sure any chlorine was gassed off. I always have RO ready and just mixing the gypsum and epsom is simpler.
Must mention I only do this with mega crop and in soil I didn't have to do that with flora flex nutes