1st time hydro grower. advice?

I'm a first time grower with a hydroponics set up. I have a DWC/topfeed cabinet thats 36" tall x 31" wide x 20" deep. I also use a fogger that came with my set up. I planted 8 seeds, 3 Jacky White, and 5 Fruit spirit 18 days ago. I'm using a 180 watt ufo LED light that is a little less that 3 inches above the tallest plant. it has the whole spectrum but is about 80% red and 20% blue (i know its supposed to be the opposite for vegetative and mostly red for flowering but I didn't find that out til later :/). I have my droppers set to drip at a rate of about 3 drops every 5 seconds. I have a few general questions that I would really appreciate some advice on. heres whats normally going on in the cab.

temperature was a little tough to control at first but it stays at around 77-78F when the light is on because i have an AC unit in the room and i crack the doors to the cab a little to let the cool air in. when the light is off and the doors are shut it can get up to 86F but I've never seen it go higher than that.

my pH level stays pretty consistent at 5.5-6 ( I have a manual pH tester with a solution you add to water from the reservoir in a little vile, shake, and compare color to the chart)

I'm using a nutrient solution called "moon dust" with an NPK of 19-8-13that came with the cabinet. it is supposed to be a proven formula to help plants grow faster with all the nutrients they need through vegitative and flowering. (I don't actually think this is the case). My plants are between 4 and 6 1/2 inches and I read plants that size should have a ppm level between 300 and 500 from water in the reservoir. 2 days ago I added enough solution to get the level to 511 and today I measured it again and it was 351. is this a normal decrease in ppm level in 2 days? also, any suggestions on the right nutrients to buy? (keep in mind I'm a beginner )

as you can see in the first and second picture some of the leaves on 2 or 3 of the plants have some discoloration and I'm still not sure what it is. I tried looking it up and I found that it could be a nitrogen problem. but if I keep my ppm level at around 500 wouldn't that be enough nitrogen? this is one of my biggest concerns.

ALSO. haha. The center plant Jacky white is easily the biggest plant in the group. Its so much bigger than some it made me wonder why its growing so much faster. The LED light I'm using has the 20% of blue lights in a ring in the absolute center of the light AND the biggest plant is directly underneath these blue lights. could this be an explanation? and if it is, would it be a good idea to maybe move some plants around to distribute the light evenly? the only problem I see with this is that the roots are pretty long and I don't know if you're supposed to take the plant out and expose the roots too much.

---I know this a lot of questions and it might sound dumb to some people but hey! its my first time! haha. so any advice anyone can give would be greatly appreciated!

man you cant really see shit with those pics how about taking pics with those leds off? it almost looks like too much nutrients. your center plant is bigger cause it has the most light. yes you should move the plants around to get even light. it wont hurt to take the plants out as long as the roots arent tangled. maybe move the light? or move the whole set up? its hard to tell those pics are not helpful at all

ok thanks. I'll try and get some better pictures up today or tomorrow. All I have is this old, crappy digital camera so its a little tough. haha

i have a fogger i have found that advanced seems to leave alot less of a salty buildup on it beond that idk i have never used a drip system. and your ppm is probly dropping because its settling to the bottom of you res. just the name moondust sounds to me like more garbage to target stupid hippies

do you have any suggestions for the right nutrients to use? vegetative and flowering? I've been shopping around but can't decide! haha

FoxFarm Nutrient line is the best, I think, for hydroponic grows. They are mostly organic, however, the solubles aren't. If you want to go organic, I'd say FoxFarm is the best. Add the solubles into the mix if you don't mind a few chemicals. Make sure you get your nutes stirred in every day by using air stones. I have also rigged up a drain on the bottom of my system so that I can drain out from the bottom and then pour back in on top. It's not a perfect solution but it helps. Your water pump for your drip system should help to keep the nutes stirred as well.

Remember to flush and renew about every 2-3 weeks to keep your water fresh, and wash out your DWC system with some 35% Food Grade H2O2 mixed at a 1 gallon water:1 dropper full of H2O2 (12-16 drops) or other sanitizer that is approved by your Hydro shop. And don't be afraid to talk to your Hydro dealers. They know a hell of a lot about growing "tomatoes" indoors and keeping the plant healthy. They'll be happy to sell you anything you need for your indoor garden.

I haven't hear many positive things about LED's for indoor grows, but then again, I haven't grown indoors for about a year so I haven't kept up on the new lighting technologies. Keep us updated and posted on your progress. I'm curious to know how your grow goes with the LED's.

Ok. So I just bought the Fox Farm nutrient trio for hydroponics. It includes the "grow big" ,"tiger bloom", and "big bloom" so I'm hoping they get here soon. You said to make sure the nutes get stirred in every day by using air stones but I'm not sure what you mean. there is an air stone on the end of the air pump, but how would I use it to mix in the nutes. I've always been a little confused on how to add the nutrients to the reservoir. I've just been mixing up the moon dust that I had with distilled water and pouring by the air stone so it would circulate throughout. I have flushed it once, but I just drained the water out using the droppers. it took a while but was effective I suppose. I didn't want to remove the lid to the reservoir because it has the plants on it (obviously) and the roots are pretty long. I wasn't sure if you're allowed to expose the roots to light for too long, or get them in contact with anything else so I couldn't clean the reservoir. How would I go about doing that if the roots are wound up with eachother? I'm sorry if I sound dumb, I'm still a beginner! haha. I really appreciate the responses.