Grrr, what is this yellowing of my leaves and how can i get rid of it

Hi dudes

I am growing for the first time under CFL's and I have a problem with 2 of my strains.

They are Citral and Domina Star and both are showing yellow leaves at the bottom (green veins) while the top seem nice and green.

I'm pretty sure its a nutrient deficiency but I dont know how to get rid of it... I really dont want to do the wrong thing!

The Blue Cheese im growing is fine.

I have them all in 5 gallon pots with a neutral soil and perlite mix. Have fed them for the last 2 weeks with a 9-2-6 feed every other watering and they are 5 weeks old.

Sorry theres no photos but any help will be a massive...er...help!

Cheers
Smoke 1 for me

Sounds like Magnesium (Mg) deficiency, but pics wuld definately help. It may just be N deficiency. Why are you only feeding every second watering, BTW?.

I'd increase the feed to every watering, and if things get worse, give a one-off treatment of epsom salts or calmag.

Cal-Mag is something to fix that....need pics though to be sure