Yellow and Brown Spots on Leaves (Trouble shooting form included)

Veterans,
I posted a thread under the "hydroponics" section this afternoon about yellow and brown spots on my leaves. I was wondering if some of the veterans could take a look and let me know what they think my issue could be. I made the mistake of posting over their in that forum. Someone was nice enough to respond but by the time I got back to answer their questions they were gone. They thought I might be possibly starving them is that what you guys think? Any help would be greatly appreciated.

General Info
Planted on 8/30
flushed in between nutrient refills (use Flora Kleen for 2 hrs before rinsing and refilling reservior with new nutes).



Equipment
a. 90 watt LED UFO light on 24/7
b. 12 inches from tops
c. enclosed reflector material
d. 90 watt bulb
e. yes conistent fresh air supply
f. I have an exhaust fan and a cirulation fan
g. reservior size is 32 qts
h. I use hydroton

Nutrients
i. Yes I rinsed the hydroton before using
j. I use distilled water
k. I use GH Flora Gro, Flora Micro, and Flora Bloom. It suggests 2.5 ml of each per gallon. I put 3 1/2 gallons of distilled water in my reservior and just used 2.5 ml for the 3 1/2 to 4 gallons because they are young and did not want to risk over fertilizing
l. ppm yesterday was 131 I think. And, today it was 79
n. temperature of of water is always room temp
o. yes ppm fluctuates a little
p. I check ph twice a day (one in morning and once at night). I may have to add PH once or twice during the week but it stays pretty consistent. I don't have a pen. I test with the kit and make sure it is at the appropriate color.
q. not using foliar feed at this time

Grow Room
s. size is 36'' tall x 31'' wide x 20'' deep
t. the temp is currently 81.3 stays at that temp (occasionally down to 79.1 and rarely up to 83).
u. no signs of insects
v. roots are long and white and in the reservior.

Strain
w. Northern Lights and Pandoras Box
x. from seeds
y. not autoflowering

You're only feeding them about 1/3 of what you're suppose to give, so I'd guess that you'd need to give more ferts. Also the leaves are kind of pale green, another indicator that they're not getting enough food. Try taking the fert dose to about 3/4 of what is the max and see how they respond.

ok first things first, a pH pen is a MUST for hydro!

when using distilled, you MUST use calmag+!

i'm not a hydro expert, so take this with a grain of salt, but i believe that when you have PPMs that are that low that means the water has nothing in it (or something like that). distilled is basically pure water. your plants are burning up any nutrients that you are adding quickly.

you might want to keep an eye on the res temps. i think 70F is a a good temp to aim for. again, not a hydro expert.

hopefully one of those experts will chime in.

good growing!


-shake

Shake, doesn't GH have calcium and magnesium already? The micro has calcium and Bloom has magnesium, according the the GH website. Looks like the plants just aren't getting enough of the good stuff though. A pH pen is a good idea.
GENERAL HYDROPONICS

Thank you so much for you feed back. I got the Cal Mag Plus yesterday. How long does do you think it will take to show signs of a change In the plants?