help save my plants

my plants are dying. of something. I grow in soil, with a 400 watt hps.
80 degrees. I have tried to resolve this problem the best I can but plants are not responding to any fert. help

anybody?? what gives with this yellowing?

looks like you got little dots, ne bugs , spider mites?

Check the PH, it looks like the its off.

Is the plant growing?

PH is 6.8-6.6, I have heard of lockout, but I don't know how to fix it.

flush flush flush

Ya know I added some 1-3-3 in a large amount and it cleared right up, some of the bottom leaves are still fucked but other than that it looks good. I think I just bought some shitty soil with no nutes. And I was scared to add more. I just blasted them and they came back.

P.S. also treated for fungus gnats, not pretty.