Brown/Silver spots

I have looked all over, and studied every source of problems I can find, and just can't find anything that resembles my issue, and makes sense for my situation.

Some quick background. I am running a 250w MH with a 14k kelvin bulb (little more blue than a 10k which I understand is a good spectrum for vegging). The light is actually as high from the plants as I can get it, I hang a fairly accurate digital thermometer about 3-4 inches above the tops of the plants, and it fluctuates from 80-88 degrees, with the lights on, and drops to around 75 degrees with the lights off. I understand this is a little hotter than ideal, however what I have read (and this seems to make sense from their conditions int he wild), that during veggitative stage, these higher temps shouldn't be an issue till it gets over 90-95 degrees. I don't think this is a heat issue however because it seems to effect the older leaves, and the new growth at the top of the plants looks fine as far as I can tell. There is a box fan pointing at the wall behind the plants, which gives them fairly good air movement, and hopefully helps to strengthen the stems. Till I can afford a real chiller, there is little more I can do to bring the heat down to closer to 75-80 consistently. About 5 times a day I mist them, which brings the temp down to around 75, though evaporates in 20-30 min or less and they are back up in the mid to high 80's.
I used a potting soil made by Whitney Farms, in 1 gallon containers. I water twice a week normally, whenever the soil down to about 4" is dry. At around week 3 I added 1/4 the recommended fish emulsion, and haven't added any nutrients since, but have another batch of 1/4 strength fish emulsion mixed up to feed them tonight (I planned on 2 fertilizations like this in the veggitative cycle). I use 100% RO/DI water with 0 TDS, and though I don't have a tester, with 0 TDS I'd imagine my water is right at 7 ph without nutrients. I believe (though I threw the bag away), that the soil was listed as neutral, so I assumed it had a PH of 7 without additional nutrients.

That's basically it as far as background info that I can think of. Here are some pictures of the issue I am having. I'm sure they will do a much better job than any description I could come up with

Micro nutes def like copper, boron, etc. This is a fairly common problem with RO should clear up with nutes if your using organics. plus the new growth looks like it is having a pH issue get a meter asap. Need to bring the water down to 5.8-6.2 if possible with RO so nutes can be absorbed with it at 7 almost everything is locked out.

Thanks a bunch for the response! Went and got a PH meter, which is reading a soil PH of exactly 7, which is what I had expected, but I didn't realize that I wanted it so much lower. I also picked up a meter which claims to test NPK, which is saying I am around 50ppm N, and 4ppm P, and 50ppm potash, which strikes me as a little low in general, so I'm going to up the concentration of my fish emulsion fertilizer, and maybe frequency, once I get the PH lowered.
Is there anything you specifically recommend for lowering the PH? Seems like there are a lot of different ways to go about it, any particularly better than the others?
Anything specific I need to add to introduce more micro nutes? I had assumed what I needed was probably going to be coming from the soil, but if I'm incorrect, and it's not something in the Alaska brand fish emulsion (5-1-1) I give them, then they aren't getting it at this point.

Edit: and to be complete, I turned my box fan down from high to medium (I got concerned that it might be causing some wind stress to have it going all the time), and it actually brought my temp down a bit. I dunno if it was the fan motor adding heat, or if it was so strong that it was sucking the hot air from the vent right back in, but I still get a mild breeze action in the plants, and the temp is much closer to ideal.

So after doing a ton more research I'm finding that the majority of advice for lowering PH are not really geared toward already growing plants. The vast majority of solutions require mixing things like peat moss into the soil before you plant in it. The one thing I found suggested adding a small amount of vinegar to my waterings. So unless someone pipes up here with something better I will start adding vinegar.

I'm left with one question though. Everything I read says that if you aren't getting micro nutrients from the water/soil, to use hydroponic nutes which should have everything the plant needs. However I have checked the local garden stores, and because of the legal status, I simply can't find these substances locally. I have a book by Mel Frank, which is fairly detailed (though it implied that a PH of 7 would be ok, when the info I am getting here is that at 7 I am still locking them out...), and he claims that miracle-gro for tomatoes contains all but one of the trace elements required (think boron might have been the missing element). Anyone aware of any common non-hydroponic mixes which will provide all the required micro nutes, or maybe a few I can mix to get all that I need?

You might have a fungus like Powdery mildew or Downy mildew. Spore can spread to other plants quickly. A product like seranade will work. Remove plants from grow room, clean grow room to remove left over spores. Then put treated plants back in the grow room. Use it once a week til the problem goes away. Also Pyrethrin fogger Bomb will kill any thing moving.

That from tap water .. i would do half tap water and half RO water .. the problem will be done in 5 days ..