Slight problems with NL

I have 5 NL. 430w son, 79-83 temps, 50-53 % humidity. Having issuse with high ph. And now as you can see the plants are a bit light and kinda drooping a little. Any suggestions would be great. Not trying to waste all kinds of money. Thanks in advance

crinkling of the leaves in seedling stage is very common although the upturning of the edges of the leaves on ur plants suggests heat stress, how far away do you have that hps?

18 inches from tops.

i have issues with ph getting too high also. Almost daily i am having to put in ph down

ive heard of adding something as a buffer like vinager or dolimite lime or something, before you ph the water. this will help to keep the ph more steady. i dont really know the details or what exactly you should use as a buffer, so you should research it more. im pretty sure this is what you need to do though. are you using reverse osmosis water? because that usually makes ph fluctuate more.

I am using distilled water.

whats a good way to lower temps?

a big ph jump either way will stress the plant but I can't really help you with ph in hydro as I've only ever done soil. Someone ealier suggested a fine dolomite lime and vinegar but that only works in soil . But, i dont think ph is the problem , 18 inches above the canopy is still very low for delicate seedlings, move it up to 22 inches and monitor the difference. Hps generally isnt as good for seedling and veg as cfl's as the hot gaze of hps can damage them.
extractor fans are the best for heat control as well as fans in general but you said that your temps 79-83? thats not too hot at all, put your arm under the hps where the seedling are and leave it there for 4 minutes, if your arms getting pretty hot then you'll b able to see how your seedlings must be feeling.
hope that helps and post me back any more questions you hav

i bet if you switch to tapwater this will solve your ph fluctuating so much