Unknown plant issues, please help

Hello everyone,
long time member, first time posting.
This is my third grow. Here's some info:

growing medium: fox farm ocean soil.
age: three weeks
water: distilled
lights: 400 hps.
pot size: 5 gallon
Temps: 72 degrees low, 86 high.
Vegetative state:lights on 24/7
Nutes: started a week ago with botanicare grow formula and magic-cal.
watering schedule: nutes, water, water - three or four days between watering.

wind provided by fan, also running humdifier at 30 percent humdity in the room.

pics below are four different plants out of 13 currently growing. Just started botanicare grow at 1 tbs per gallon. Also adding 1 tsp of magi-cal along with the bontanicare. Did not use nutes the first three weeks because fox farm ocean forest soil as organic nutes in it already.

Just leeched the plants in question this morning, of course will take time to see what's next in store for me.

I do not have the funds to currently buy a digital ph tester. I do realize how important it is for ph levels, but cannot purchase one until this grow has succeeded.

Leaves are yellowing, with a bit of necrotic spots appearing. Is it

A. nute burn
B. needs more magnesium and calcium
C. not enough nitrogen
D. none of the above

Thanks for all and any help
Happy Smoking!

A. Not nute burn
B. Most likely
C. Likely
D. GET A PH PROBE ASAP!

You can get a probe off ebay for like 20 bucks. Go ahead and give the about 3ml of Cal-Mag+ per gal of water and you'll green up soon.

Thanks Mr Ganja.
Would you be kind enough to suggest since I just leeched the plants a few hours ago, when I should give it a magi-cal boost?

Thanks again

Can anyone else chime in as to what they think is going on? I leeched the plants yesterday, added a little magic-cal (5ml per gallon). yellowing is moving on up the plant now.


Also, If I get the digital ph meter from ebay for $20, is it a soil or water ph tester?
I'm guessing the trick is to buy the cheapo digital meter and test the water runoff when leeching. Am I correct in this assumption?

Thanks in advance to all!