HELP - My 4 week old Kush has yellow top leaves

she is about 4 weeks old, under 2 6500k T-5's with 100 watt CFL 6500K supplemental lights. The humididty ranges from 40% to 60%, temps stay right around 80-83F. It is currently in a 1 gallon bucket, it is in a mix of 1/3 miracle grow potting soil (with 5-3-3 nutes), 1/3 reg potting soil with no nutes, and 1/3 perlite. I also mixed in 1 tablespoon of epsona (has all 15 micro nutes). The miracle growsoil is really 1/3 strenght because it was mix with 2/3 with stuff with no nutes. It has 3 sisters in the same soil mix that are green, no yellow at all. 2 other the other Kush seem to have smaller new groth and shorter distance between nodes. Like the top is getting compact. I have been watering them only when the soil gets real dry. i water with distilled H2O Ph about 6%.

The last time i watered i added Canna A & B nutes at 25%. They all grew like 3 inches over night but then one got the yellow leaves at the top and 2 other got really compact growth at the top. Over nute or not enough nutes????

also does anybody know for sure, from exp how often to water, i have read that the soil should get really dry before watering. the top soil is dry, and when i stick my finger in it is dry to my second knuckle but moist near my finger tip, not wet just moist. should i water at this point or let it dry more?

1 pic shows all 4
1 pic shows the yollow tops
1 pic shows the top small compact growth

sorry so long- just wanna make sure you have all the details

if you know what the deal is from experience with the yellow leaves and when to water please let me know. thanks

looks like MG defect but im not sure i dunno check the GrowFAQ https://www.rollitup.org/view.php?pg=faq&cmd=article&id=588

thanx -i have read through a bunch of post and forums including the grow faq- i was hoping someone could tell by looking at the pic that had "been there done that" as they say, a picture is worth a thousand words. i dont want to f the plants up if i get it wrong.

i watered it with distilled H2O with no nutes and it started clearing up. I dont like Canna A & B, i have had nothing but problems with it in both hydro and soil applications. swithcing to fox farm.

Make some water up and feed her orthem nothing any higher than 5.5ph once it ha regained its normal growing and the yellowing disapates feed 6.5 plants grow best around this ph level but it may take a couple of week.

sounds good tyke - i'll give it a shot