your microbe population is lacking and your probably feeding them wrong and not watering in at 6.5 those new pics today look kind of burnt so thats my opinion. Then its the lighting if the roots are ok. I doubt it s the lighting. Dont know what the algae bloom booster is. I dont test my soil i just dont need to so I dont know about all of that stuff. i think that they became sick and you kept watering them and now theres an issue with that. Maybe let them dry out and water a little less more often and let things mellow and practice on your watering tenique with proper nutrients in the correct ratios and let them finish out.So far, I tried synthetic fertiliser once and it didn't work, the rest of the waterings I've been putting organic stuff in.
The algae bloom booster has a lot of microbes, micro nutrients and amino acids that aid the roots in supplying the plant with nutrients, also the liquid worm fert has humic and fulvic acid along with microbes that decompose organic matter and feed it to the roots.
If they regulate the ph, why does it matter to ph every watering?
If the soil becomes too acidic, wouldn't a higher ph water help to make it more alkaline?
Btw my tap water is pretty hard, loaded with calcium, magnesium in majority and other trace minerals, that's why i havent considered adding cal-mag.