Leaves Turning Very Light Yellow- HELP!- Pics

Ive got 10 plants growing, and about 8 of them are turning very very light yellow. I'm not talking about a little color change- this is totally yellow Im talking about.

Ive attached the picture where you can see the problem, but in person it looks 10x more drastic.

Watering every 4 days or so.. under 23w CFL's. Only using fertilizer once every 3 or so feedings at 1/4 strength.

Also, at least half of the plants have really really slowed down their growth- or even stopped completely.

Any ideas???

Whats the fertilizer? And, what are the temps like? Are you checking the pH of you water?

looks like possible ph to me to where did the yellowing start

Ive been using miracle grow all purpose. I think a problem might be temperature because its been very hot in the room- probably around 85 degrees. Im working on lowering the temp right now.

mine had the same problem, I adjusted the PH to about 5.8 and used Grow Big and it greened right up in about 2 days! Try something like that first

The yellowing starts at the edges of the leaves, and now all the new leaves are totally mustard color yellow. I used a little vinegar diluted in the water from the last feeding to try to lower the PH just a little bit.

It looks like nutrient lock out, more specifically, a nitrogen defiency.
Once you balance out the PH should clear right up.
You are on the right track by adjusting the ph.
Keep us posted

sounds n looks to me like evrything is outa wack. first off its obviously difficiant in nitrogen and phosphorus. most likly its difficiant in potassium aswell. the fertalizers your using are not the best but should be more effective than that. if possible get a n-p-k pack of nutes from a hydro store. if thats outa the question, make sure the nutes your using have a high source of n-p-k. dont dillute the nutes your using so much and nute every other watering. use 2 cups of liquid per watering or feeding. your lights are not producing enough lumins either. if using cfls stick with wattages over 55. and ofcource make sure there is ample air circulation, the humidity is around 50%, and the heat stays at a constant temp (no higher than 75, n no less than 60). best of luck

Thanks for the suggestions. So, everyone seems to be pointing me towards feeding it some more fertilizer. I was planning on stopping it for a while.

The stuff Ive been using is 24-8-16. In a week or so I was going to switch to 15-30-15. Which do you think I should be using now?

Thanks for the suggstions. WIll do.