Another yellow and brown leaves post!

[RubySlippers]

Hello,
All 4 of my plants are a bit sick, with two being worse off. The bottom leaves are yellowing and have brown spots. I've been reading other posts on the forum and re-reading articles on the website and I I'm at the point where I need some outside advice. In the last week I started treating them for fungus gnats with Neem oil. The number of bugs inside the tent have decreased, but it's a constant battle, it seems. My tent is in the basement and the gnats really fucking love it down there. I also have found a few moths in there as well. There was a vent open so I closed it. Hopefully they'll stay out. Anyway, Ph in and out has been pretty consistently around 6.5. Distance to light has been about 18" with variation here and there. I started using CaliMagic consistently when I first noticed the yellowing, thinking it was a cal/mag or iron deficiency. It seems to be getting worse. The leaves don't fall off, they just shrivel up.
I water each 5 gal bucket with about 2L (.8 gal) as needed (I check for dryness with a finger) then spray the top of the moist soil with Neem oil. Half-strength nutes every other water. I don't have my grow journal with me, but I think I've been doing full strength CaliMagic for every water. Maybe I'm over doing it? Any help is appreciated!

[RubySlippers]

I've noticed some white powdery build up on the outside of the fabric pots, at the bottom. I believe this to be mineral deposits from my hard water. At this point I'm thinking of flushing the plants. Good idea, or no?

[9fingerleafs]

That's the best idea so far. I think your problem are salts and mineral buildup. Too much calcium makes that white residue and too much potassium can cause the yellowing and the brown edges. Try flushing with at least the same amount your pot can hold. And go easy on the nutes. It is way easier to give the plant too much than to underfed good luck ruby.

[RubySlippers]

Thanks! The drip pans was using originally had high sides so I think that prevented the pots from drying out completely.