Looks like spidermites. Look on the bottom of the leaf for bugs and white web.

If no bugs then what kind of water. PH is not your problem or low water. Looks like you need some Cal-Mag plus. Or nute lock out from water source.
LOC NAR on probation Reviewed by LOC NAR on probation on . goldish brown spots have pics looked at my plants today and they where fine 12 hours later i noticed goldish brown spots here is pics in a bubbleponics 6 plant system 600watt hps ph did go down today 2 5.75 and was 2 gallons short on water re filled and added more nutrients Rating: 5