Listen, if you have not used calmag up to this point, you’re not hurting anything by using it. Tap water or RO. I’ve used both and used calmag every single time. I don’t runoff dump 95% of the time unless I overwater and need to remove some from the tray because it didn’t soak over time. I also used GH Micro regular with tap and not the GH Micro Hard Water, didn’t matter, shit grew without deficiencies. Calmag is your protector from pushing limits if you want my opinion about it, they use a crap load of it for multiple processes, so why skimp or not use it. It is only when you go way too hard on calcium will it cause a lockout, but it will only lockout other positive ions in the soil.
Iron is another positive ion. It can cause yellowing. Ph being too high will make it less available. Anything 7.5+ is basically going to show deficiency. Especially in a stage when she is demanding it.
Lo and behold that Iron is also in the process of creating chlorophyll. Now, CaliMagic has chelated Iron! So don’t drop it out, keep using it 1ml per gallon. Calmags usage is to prevent secondary nutrient deficiencies. There is a reason Magic is in the name. It’s a key nutrient to use all grow to accommodate how much abuse we home growers put on these plants. A protective barrier to deficiencies.