First Time Growers In Need Of Diagnosis

I've been doing some research to try and self diagnose the problems with our plants. from what I've gathered they could be suffering from either nute burn, nitrogen deficiency, magnesium Deficiency or an over exposure to heat? We're kind of confused as most of these problems have similar symptoms making it hard for in-experienced growers to make a firm diagnosis and we would not want things to be made worse.

We have been growing in soil mixed with perlite in a small closet like space under a 400w HPS with an 18 hour on 6 hour off light cycle, we know ventilation has been an issue so far, we are on that and sorting a decent in/out take, and for the meantime have had two fans circulating the air around the growing environment.

The temperature was slightly higher than what we had desired because of this (hitting a peak of around 32 Celsius 89.6 Fahrenheit) but we seem to have that under control now peaking around 27 Celcius 80.6 Faenheit. The plants are reasonably small, around 7" and we've only fed them with nutrients (high N) the once so far (we were a little naive and fed the plants almost a full dose of our 25-15-15 fertiliser at this point) since this time we have turned back to purely feeding the plants with just water. As of now They seem to be looking/developing new leaves ok but the coloration is a little patchy in parts of the leaves (please see pictures).

We are growing one 'Vanilla Kush' and one 'G13 Haze' the Vanilla Kush strain has started showing signs of yellow amongst the majority of the top leaves (this is the smaller plant in the pictures.) and the G13 strain has random patches of slightly dis-coloured green over the majority of the top leaves, we first noticed this plant was having problems when the first two bladed leaves appeared to be burnt at the tips i have included pictures of this.

Any light which could be shed on this situation for us would be greatly appreciated as we just want our little babies to have a good little life.

cheers guys with your help we'd love to get these girls back on track.

Looks like nitrogen burn. You want to be sure and use a good potting soil for seeds and clones. They don't need any nutrients till they get a foot tall or so. Most potting soils have plenty of nutes already in them. The only thing I use is a light dose of vitamin B12 anti stress nute.