There was brown spots on fan leafs, pH level is 5....

I agree with Cbalderson using a product like hydroguard or Uc roots is almost essential to happy health hydro growing... They are products that create a more stable and healthy environment for your roots.. Also consider blacking out your containers and even maybe the top part as well.. In my experience with LED they can penetrate the claypellets and shine light into the reservoir, very bad. You want your water to be in the darkness depths of hell basically. Just some food for thought but yes I highly recommend using a rootzone enhancer... It keeps your water's PH more stable as well, your ph will always fluctuate but I found after finding a sweet spot of UC roots to water. My water is much more stable requiring very little adjustments and in turn I use less of the ph up and down.. I check ph daily you should too, it's a good excuse to look at your plant. Iv'e had great success with hydro so if you have any more questions leave a comment on my diary. Good luck and happy growing :)