Yellow Spots That Turn Into Holes

Here is my grow info:

Strain: G-13 (maybe a hybrid)
Moved to flower about a week ago
400 watt HPS about 2 feet from the plants
5.5 - 6.5 ph/Piss colored (not exact, using chemicals to test right now, no meter)
18 gal reservoir, Distilled water (adjusted)
Ebb & flow system, 15 min 3x day
GH Flora Series Nutrients, recently changed to Transition phase and flushed before hand
8-9 week old clones, four in one tray

I started getting these yellow spots a few days ago and they are resulting in holes. I have attached a picture of how the leaves look originally and one showing what happens to the yellow spots after a day or two. The yellow spots are also spreading quickly.

I have checked for bugs and I am pretty sure that there are not any. I dilluted my nutrient solution thinking that it was nutrient burn and that did not seem to help either. I am going to try flushing the system right now to see if that helps.

The last two pictures show that the problem is on brand new growth as well as old. The second to last picture is the new and the last picture is the old.

Any help will be greatly appreciated!

whats your temps and humidity look like? it looks like your leaves are drying up because of those factors

The temperature is mostly between 75 and 85 and I have been using an AC unit to keep the temperature down. There is also an exhaust fan attached to an enclosed hood to help keep the light cool. Now that you mention it though, the problem did seem to start when I switched from T12 lights to a 400W HPS. It is currently about 24" above the plants. Should I raise it higher?

The humidity is mostly between 50 and 60.

Do you think that the temperature/humidtity fluctuation could be a problem or is that range small enough?

No answer, but I actually figured out what it was. BUGS! There were bugs in my reservoir water today. Really gross.

I am not sure what kind of bugs these are. They are white/yellow with little legs and round, tick shaped bodies.

I am going to get a Mosquito Dunk, and I should probably try Gnatrol to run through my hydro system according to my research. I already sprayed the foliage with Earth-Tone Insect control but I am worried about the roots.

If anyone has any ideas how I might have gotten these, let me know.

Dont know but I had the same thing on 2 of my plants out of 6. I just cut damage parts and sprayed with insecticide, so we will see. I take my plants outside to water so I think this is where my problem came from. Never actually seen bugs but its the only logical thing.

I think your roots should be fine. I dont think the little shit heads would be able to munch on roots under water.
They probably got stuck in there.

i would bet you brought something in from outdoors!! keep the indoor grows inside and outdoor grows outside. i would not even bring any clones in from outdoor plants just to risky especially when you got a great indoor grow going.

I did bring some other household plants in from another room. Thought my cats were eating it, but it turned out that the bugs spread. I treated them all and completely cleaned the grow room out. I think the bugs are gone. I fogged and used Azra Maz in the resevoir. Also hung a fly sticky trap.