First Indoor Grow 3 of 4 Dying

Hi, I have 4 plants. Put them on 12/12 light schedule and 3 started wilting, tops were yellow and have now turned yellow and b rown all over. The ony healty plant is my Purple. The widow and 2 cheese plants previously seemed ok but did have purple stems? They are all in a preflower stage. Used Fox Farms Bloom Food. I have pics but need to figure how to load up.

Any suggestions.

u prolly over fertilized or over watered or heat of a number of things..need pics to tell

Yes you are right I did overfertilize. I am trying to save one swiss cheese by flushing and it does look a little better. I bought one of those cheap #3 testers to confirm. I am soooo sad. I probably should buy a meter for testing but they are pricey. Thank you for your response. This is my first indoor grow. I didnt realize there was so much to learn.

dude 40 bucks would have saved ur plants for a tester

^Yep, you probably are killing them, and starving them, with low PH. I can almost guarantee it.