First grow ever yellow blotches on leaves in coco please help

Hey guys this is my very first grow and i am having a problem with yellow blotches showing up throughout the grow so far. I am growing in coco i have been phing my purified water to 5.8 bringing ppm up to 175 with cal mag (about 2ml a gal) and up until yesterday i was going off general hydro flora series feeding chart on their website. I decided to give heads Lucas a try and watered last night 6/9 ppms came out at around 720 . My question is what is causing these blotchy yellow spots? I am using 2 1k w hps lights i have 6 more 1k lights that are off right now about 3 feet above plants temps range from 70-81 rh between 45-60. They seem to be growing fine but these yellow spots got me worried.. Also how would you say my growth is going bigger plants in 1 gal are 2 weeks 2 days old solo cups 1 week 4 days old from sprout. Smaller plants in solo are getting half strength. Thanks in advance for anyone with some helpful info i appreciate it.

Here are pics of them out of the mh light they look a lot green when not under the 1k lights. Am i just over reacting and they are healthy i am just paranoid i have invested a lot of money into this.

That's some powerful lighting! Plus in coco, it seems to be the very beginning of magnesium deficiency. I use the same nutes, and lucas, the mag is rarely enough, and im in soil! With those lights, i'd say you can go the full lucas route at 8/16, and maybe some extra cal/mag, or epsom salt once flowering, for your extra mag.

i appreciate the reply that's what i was thinking it was a mag def. As far as Epsom salt goes is there a particular type to buy or stay away from. i will be cloning these and running about 120 plants first harvest that's why i have 8k w lights. Hoping for at least 15 lbs hopefully more but i dont want to get my hopes up vegging for 2 months. Thank you again for your insight.

Whoa, that's some serious weight! best of luck on that!!! As far as epsom goes, it's all the same, just make sure it's original or whatever they call it..nothing scented.

You will also discover down the road that the head and Lucas formula whilst do work but my opinion is they'll leave ya hanging about weak 4. Rock either the 321 or 111 something complete and balanced.. I just broke off Lucas and rolling the 111 this round and will say my week 4 is on cruise.... Much success!

Looks like you're short on Mg...epsom salt should do you right. Otherwise, you have a nice collection of ladies there.