HELP! Yellowing and brown spots on top and bottom growth

[GoGrowGo]

I need some assistance identifying the problem here. I am unsure if this is disease, ph, nutrient deficiency/toxicity, bugs, fungal, bacterial, etc. These are growing in an ac infinity tent (70-73F, 55-57% humidity), in happy frog soil and I use general hydroponics nutrients. I feed these every 3rd day (1/3 gallon each), skip the following day, light watering PH 6.0 (1 water bottle each) and repeat. The brown spots first showed up on the plant in the back about midway up the plant. The next day the leaves at the top flower site turned and it showed up on the plant front right. Yesterday it showed up on the 3rd plant which is a few weeks behind growth stage of the other 2. It should be noted that these are 3 different autoflower strains in week 10 and the rear plant is near the end of its life cycle. Any help is much appreciated.

Thank you!

 

[Rwise]

With soil in flower run the PH at 6.5-6.8, add cal/mag.

 

[SoOrbudgal]

Nice looking not to worry to much like you said and the way they look they are near done! Time to just water clear out all those ferts/nutes allow the plant to dry me personally i would'nt give any more nutes. Those leaf are dying she's taking all the vitamins out from the plant cells and making those lovely buds. Be happy man you got a nice harvest in less than 10days on one of those plants. And yes add cal/mag to those not so done ones yet.

 

[GoGrowGo]

Thanks for the replies! I will flush them all today with 6.5PH water and hope for the best.