Need help. PICS POSTED

This is my first grow and I am doing DWC. I am in the beginning of week 4 and these problems started at the beginning of week 2. At first they started on the first two serrated leaves and i thought it may be because of the light foliar spray I did at the beginning of week 2 but the problem developed on leaves that came after the foliar spray. So I checked the PH and found out that after I would balance my nute solution out at 6.0 the PH was rising up to a 7.5 so I corrected it to 6.0 about 4 or 5 days ago. But the problem is still appearing in new places. Brown, light green, tan, and white spots and holes that look as if it were burned. my ppm is between 430 and 460 and comes out of the tap about 60 to 90 ppm. I use tap water for my solution and treat it with AquaSafe I have not heard of it doing any harm to plants. My light is a 400w HID that I have decreased to 75% power. Humidity stays between 40 and 60 percent and temp between 70 to 81 degrees.

ANY HELP WOULD BE AWESOME!?!?!?!?!?!?

Those spots can be caused by pH fluctuations, focus on maintaining a constant pH, and don't worry about the old damaged leaves. They will not repair, just focus on the new growth.

GL.

C90

the plants look good it may just be caused by something has simple has getting a bit of feed on the leaves, but dont worrie about it the tops look good coulour so just get them to the height you want then flower.

also get the filter high up in the room it will be takeing any fresh air round the plants straight out the room inlet low filter high has possible heat rises

Yes I have been slacking need to get it up.