New to hydro Humidity hard water or nute burn????

First time doing hydroponics not sure what's is causing my leaves to dry up any curl my temperature and humidity seemed fine. I have 400 watt metal hilide with lights about 2 feet above plants previously had humidity at 40%.. My ph is about 5.9 and I'm using general hydroponics duo floura series in a 3 gallon bin .roots seem fine however my well water is running about 240 ppm and I think I might be mixing too much solution in my water. Now I'm noticing yellowish centers in my leaves and they feel dry to the touch and new growth beginning to Curl . I also can't seem to control my PH levels They seemed to go back up after a day or two And my temperatures range between 65 and 72 should I put all me half strength solution guys I need your help she also seems on the light side of green as well she's not dying but doesn't seem too happy scared it might turn out of the worst
Any suggestions from the pics??????

I ran the ph at 6 for years until someone came up to me about 1993 and told me that the proper ph for hydro is 5.8 It does look "like" the nute level might be about 1/10th too much in the res.
Start the ph at 5.5 and dump it at 6.3.

Running your res above seventy can cause a microbial activity that can result in the lockout of some nutrients. The answer to this is to clean the res and replace the res water every 4-7 days. Also you may have to find a way to get the res down to 70f. I would start the res at sixty F from the tap.

Brings back memories...bad memories. I solved problem by keeping my addiction to gadgets out of growing and going back to soil .

Easy does it. He's right your res temp
should be low 60s. You can also use GH hard water nutes. 240is high bro. Ive been there. I actually went to buying distilled water for a while til i could afford a ro filter. You can keep the cost down by halfing your water with distilled. This will help stabilize your ph also. Make sure you use plant ph up and down not the shit for pools. They use sulfur in that, not good for babies.