move to CFL box, yellowing leaves

since my friend put his babies in a cfl box, they have been doing well but looking a bit less green and more yellow in the leaves. his box is two 50 gallon rubbermaids on top of each other but the babies are raised halfway up. there is a total of 8 x 23w 1600L (2700K) and 2 x 43w 2600L (2700K)
totaling:

268w 18000Lumens. the square feet of the babies is about 3 ft across 2 ft wide probably.

also, they are about 1ft tall and quite bushy (LSTing) and he has induced 12/12 for about half a week to start sexing to rid any males. sorry, he doesnt have a camera :(

should he be worried or are the babies just adjusting to the warmer lights? none of the leaves have fallen off and its the new growth thats a pale green, not necessarily much of a yellow but still.

before they were under a bunch of 6500k 4ft flouros .

of course there is air intake outake and also the babies are all in 3.5 gallon pails. thx

New leaves yellowing could be related to nitrogen problems instead.
Old, low leaves yellowing on a vegging plant is more indicative that they're not getting enough light.

hes yet to give them any extra ferts, they have been growing in potting soil and perlite 50/50. is it correct that for vegging good nutes should be around 20-20-20 and for budding 10-50-10 ? and dont you stop 4 weeks before harvest?

he wants to grow them effectively but with as little nutes as possible, and as cheap as possible.