some thing is wrong please help

can anyone tell me what this might be the tips of my leave are turning down and there is small yellow spots showing up on my leaves its only on two of the six plants in my hydro set up the last two on the drip line i'm useing earth juice and fox farms big bloom the plants are 26 days old i have added some pics that might help i have moved the lights up today they were getting close to the plants but i do not think this was the problem i also topped off my tank yesterday when i first saw the problem thought this might fix it my ph is 5.6 room temp is 78.6 i have co2 in the room that i added a few days ago i have also been adding sm-90 for a root problem that was a week ago and everything looked good after i used it till yesterday when i got home

as far as the bending down, i would say that it is rather normal.
did you notice the tips bending down a few days after you watered? because the tips of mine bend down after about 2-3 days without water.
when you water your plants, they should stick out more. if not, it is ok.

the yellow spots look like nute burn. dont over feed your plants.
or
your plant could have nitrogen deffiency, but i think the leaf would look alot worse if that was the case.

its a hydroponics drip system,i dont water them, i added another gallon of nutes yesterday because i read somewhere that it had a potasium deff prob i think that is where the spots come from,hopefully its just the temp,,it gets pretty hot during the day in there ,maybe thats why the leaves are curling down

Looks like heat stress to me on some of the leaf tips.