Current culture help!

I have a 400 gallon 32 site current culture system with 32 plants under 18 hps. I'm having a hard time figuring out exactly what is wrong with what I'm doing. I'm using current culture nutes now but before in my last run I was using heavy 16 and had no problem what so ever and everything turned out great but this time when I tried using the same stuff I got, what I think is really bad nutrient lockup, this brown sludge material that coated everything and turned the roots and stained the rock wool cubes even some of the pearlite brown. After I cleaned the whole system and refilled it with current culture solution my plants are seeming to be not getting any bigger and some of the leaves are starting to curl up. They all are standing straight up still but I cannot figure out what I'm doing wrong. My water temps are at 68°F and I have plenty of air going through and into the buckets.

Any help would be appreciated I could really use it and if something isn't clear I can answer a question. Thanks

You're using the Current Culture nutrients this run?

What's your PPM/PH? Same strain?

Keep the strength low. Especially if they look like shit.

I am using current culture nutrients this run. My ppm is 185 and ph is 6.2. For the most part it's the same strains.

I've been reading about myco stop and just added some into the system, would you happen to know how long it takes before the bacteria starts to colonize ?

I don't like using additives in water culture. I can't answer that question.

The PPM/strength seems very low. My tap water is 140PPM. Is your meter 500 scale?

450-700PPM is usually a good ballpark. I think I used to run mine around 6-700PPM.

To be honest, I went back to coco. I got sick of fucking with shit. Drain to waste is just too easy. Lol

Yeah man I'm thinking about doing drain tables but I have the money in this. I'll look into it. Just need to get this back where it should be.