crusty white buildup on leaves of clones in aero cloner

i been noticing this crusty white stuff building up at the tips and edges of my leaves on my clones in my aero cloner. it kind of resembles mildew but im pretty sure it's not powdery mildew as i have dealt with that many times. i used to see it all the time and just ignore it thinking it was just calcium buildup. now im not so sure its calcium buildup because its growing more. azamax 5ml/quart doesnt seem to work very well on it. im doing everything the same as far as i know. keep ph 5.8 m- 6.2. just tap water. room stays 70-75 F. i dont use a humidity dome because i seem to get better results without it. i try not to even spray them much because otherwise they seem to stay too wet and the leaves turn black and kinda rot away. i use clones rooting solution 20ml/gallon. i cleaned the thing really good with bleach before my last batch, then with h202 and dish soap. then gave it a very thorough rinse. i'll try and get some pics. its not in splotches like powdery mildew. its more like little spects of white shit forming. feels kinda crusty or grainy like salt. it's not powdery at all.at on the edges and tips of the leaves. i dont know much about downy mildew but it doesnt seem to fit the symptoms.

anyone have any idea of what it is and how to treat it? could it be my mother plant is diseased and keeps passing it to the clones? she is over a year old and not quite as vigorous as she once was. i really dont want to lose her. hoping i can solve this. im always cutting clones off her and giving them away to friends free of charge so they dont have to pay for weed as much. hoping i can keep this going as we all really love this strain.

It probably is salt. If theyre not rooted yet and not growing they cant really process the phosphorous and whatever is in the cloning solution, (20 ml per gallon sounds kinda high too). Spraying anything but water on unrooted clones can stress them too Ive found.

the instructions say to use 20-40ml but maybe i'll try 10ml instead and clean the thing out again real good. one of them had this slimy shit on the stem. i just threw it out. i actually had this happen before and i always just threw the couple slimey ones out and changed the solution. never seemed to cause much of a problem as most of my cuttings root fine then they either go directly in soil or DWC. i dont really like those cubes. i do want to try rockwool though.

i went down to 5 ml per gallon. no salt buildup. thank u so much friend! one just started popping out roots today.