Cabinet grow with bagseed

Me and my brother in law recently started a bagseed grow to have a run at it before we start the good seeds we are gonna get from drchronic.com. Our cabinet that we are growing in is 3' tall and about 2 and a half feet wide by 4' deep. We have one 120 watt 2200 lumen fluro on them and we also have a few strip lights but we havent gotten around to makeing a ventilation system yet so we cant run it with all them in there cause it gets too hot. Also a few of the plants have alittle yellowing of the tips and one of them actually the leaves are curling up which i think could be nutrient lock up or over watering, but here are some pics .......
First pic is of the biggest one.

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second pic is of the tips

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Third pic is the same plant as the first.

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Now this is another pic of the yellowing of the leaves

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And this is the sick plant

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Anything?

are you feedin them any nutes... because the plant with the yellowing tips looks like its suffering from some nute burn... the curling plant could be coming from the heat.. you said theres not ventilation? how hot is it getting in there?

The average temp when the lights is on is around 80-85. Also no im not feeding it any ferts.

I'm using miracle grow, and my plants look healthy so I'm hoping they'll continue to grow. Plants need light, water, and food to live. You give them that, and they'll give you smoke eventually.

Also i was thinking of buying a 70 watt hps flood light at homedepot with a 120volt ballast, do u think that would work?

yes that will work very nicely.. but you will deffinatly need ventilation with that...you can even use the hps to veg if you suppliment it with some cool white cfl's... and about the nutes hmm does the soil their in have any nutes in it .. or maybe it could be a nitrogen def...

Yes the soil is miracle grow so i assume it has nutes in it. Also im planning on making a carbon filter with fan and also im putting another oscilating fan in there.