brown spots & yellowing leaves?

Hi there. Thank you for your time. I appreciate any feedback!
I am growing 3 auto haze in an 18gallon dwc. 600watt hps. Temps 80 day/70 dark. Res 62-68 degrees. Botanicare grow & karma at half recommended dose. (Switching to bloom next res change).

MY PROBLEM...
These brown spots started 2 wks ago. I adjusted lights, fans, nutes, & temps. I fixed a few other issues but these spots are slowly starting to appear on newer growth now. And the leaves that were damaged early on are now yellow and brown all over.
I looked up thrips bc I found 2 little winged critters on the glass in my hood. So I am getting the Hot Shot No Pest Strips from lowes tonight. But do these bastards cause the leaf to turn brown??
If not what else could this be?

Pics are below...have to restart my phone so it finds my sd card.

Here are the pics...

Whats the ph bro
?

It seems to stay around 6.1...I bring it down to 5.7/5.8 every day or every other day.

The ph spiked a couple times to 6.7 the first 2 wks before I started adding nutes...but since I thought those spots may be from nitrogen def I added some grow nutess. The ph seems to stay around 6.1 now.

looks like maybe rust fungus?....are you using city water?

Yes I have been just filling the 18gallon tote, ph the water, add nutes, ph again...then add plants. I am setting up another tote with a bubbler in it tonight so it can sit 24 hrs and then put in res. Should I try this before I add anything to rid them of this potential fungus?