need help to figure out deficiency

hello RIU i am on my second grow and i need help as to what exactly is causing my plants to look like this i know i have a cal-mag deficiency but cant figure out if i have something else that is causing my plants to burn up.

I notice a few days ago my plants were getting yellow from the tips of the leaves making its way to cover the whole leave and leaving the veins a dark green.. also i get really burnt crispy brown spots on the leaves it has started from the bottom and it looks like it is making its way up the plant. the tops still look good good new growth and etc.... my setup is as follows

5 gallon pots- fox farm and happy frog soil mixed together
Have not feed the plants any nutrients besides a little cal-mag after the problem occurred a few days ago
600 watt MH bulb
Keep the temperatures around 75-78 sometimes it gets to 82 on a very hott day
humidity around 40 depends on day

if you need any other information or pictures i can provide thank you to anyone in advance that helps me out much appreciated.
i have the pictures attached below thanks again

Yes, what he said. Doesn't sound possible to have a nute burn from what you said and your upper leaves are not showing any warning signs of overfeeding. I'd feed them a little.

If you're using Happy Frog and/or Ocean Forest, you shouldn't have to feed for 30 days or more. Make sure your pots are draining correctly, sometimes the holes get clogged with coco or something else and the bottom stays saturated but the top can be bone dry. Next I would check the ph and if it is within the limits, then give a light feeding because it actually looks like a phosphorus deficiency. Its definitely not nute burn Bro, your plants would've burned up way earlier.

hey dannyblaze yeah they are stretched probably because i have had them under cfl lights since they broke ground from seeds... these grand daddy seeds feel out of some weed i bought from a friend at first i was upset but the weed was so fire i figured hey i just got some free seeds so i didnt really put them in my regular rotation of 600 watts they have been under 12 bulb home made cfl fixture (works good for clones and seeds) so maybe that might have some reason and as far as ppms i dont have a measure for that i just ph and usually im around 6.2-7.0.....
bugeye thanks man and yeah i didnt think it was that i only thought it was cal mag with a phosporus problem and str8dre kinda confirm my suspicions .... and also str8dre also appreciate the input man i was using just happy frog when they were seeds than when i transplanted them about a week and half ago i used the mixed of soils maybe i should just wait for the roots to take off in the soil and it will provide the proper nutrients ... thank you guys for all the help greatly appreciate it ima give them a light feeding and see if that stops them from getting worse thanks again