Hi i am new and looking for some advice!

You won't have enough height for anything but a smaller light if you go HPS. You,d need a foot from the top and probably twelve to eighteen inches between your light and the top of your plant with a four hundred watt HPS. LST would work for light management. Still pretty tight confines IMHO. I have'nt bothered with anything smaller than 600 watt MH and HPS so the LED thing is Greek to me. Good luck. Let me know how it goes for you.

I actually upgraded to a 6 foot tent. Still tho I am racking my brain trying to figure out how to work with getting temps up in the tent. So who knows. I might have to bail on the 400w and look at a 600w HPS

jnkinc said:

I actually upgraded to a 6 foot tent. Still tho I am racking my brain trying to figure out how to work with getting temps up in the tent. So who knows. I might have to bail on the 400w and look at a 600w HPS

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Well temps too low is a far easier fix than temps too high, you obviously have good airflow.

I grow in an attic so temps are always an issue for me, freezing in the winter and roasting in the summer. I use a fan heater with a thermostat, knocks itself off when it hits about 24c, this could be a good option for you.
I run my lights 8pm - 8am as it seems to get coldest between these hours.

You could also look into getting a switchable ballast and run 600w during the winter and 400w during the summer.

Also, keep in mind that temps will rise when you have plants taking up room in the tent.