Too much yellowing

Hello -

I have a lot of yellowing on 50% of my plants and can't seem to fix the problem. I grow in Sunshine Mix #4 and am growing inside with 6 1000 bulbs on a mover. The room is about 17x12. I've seen curling tips, yellowing older growth but also the new leaves are yellowing now as well. I thought i was maybe feeding too much at first because I have tip burn and so started with a 55 gallon mix of my nutirent and would add water to dilute it each watering until I was just giving water for a day or two and than start the process over again. Than I thought, with all the yellowing, (and some dead circles on some of the leaves that have yellow) that maybe they're not getting enough nuts.

A friend of mine has said it's a nut lock up and I should flush with Epsom salt. I've been reading contradicting things on this. I will post some photos asap but thought I would get this information on here ASAP.

Thoughts??

Also,they've not had very good (or any drainage until now) (LONG FRUSTRATING STORY) They are in 4 gallon bucks that are set in 5 gallon buckets to they can air out on the bottom. The roots have now grown into the bottom to the 5 gallon buck (of course). They are not always sitting in water though. I'm careful of that. I was thinking, because it's been a good five weeks with no flushing.... lock out? I'm going out to flush right now (designed my own draining system FINALLY) but want to know about the Epsom Salt still. My water is well fed with 250 ppm with out nuts. The calcium/Mag is high. (I only say this because of the white build up that occurs on a glass if left with water in it) I use something to compensate for the hard water in my mix.