i am gonna pick up a few clones and grow them up to mothers under a 175 watt hps.
the quetion is how many plant should grow in such a space and what wattage should i use.

oh and within like 6 feet is a water heater is there a way to leech the co2 it makes?

4 ft x 4 ft will need more light than 175. an hps will work... not the best move. is your water heater gas?? 4x4 = 16 sq feet...find some square 5 gallon buckets (like the kitty litter ones) you should be able to get about 12-16 in there o yeah a 1000 watter will cover 16 sq ft but for mothers a 600 mh would be great

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"GIVE ME 3 ROUNDS!! "

I'm starting the same size as you 4 x 4 but i have limited height space (only 4' again'). I've fitted a 400W HPS and am only starting 10 plants (from feminized seeds, White Widow and Mazar). I've been told that even under my height restrictions, 400W is stretching it!

I've also chucked in a greenhouse heater, a small 7" desk fan fan and an inline fan with a Carbon Filter for smells/heat.

This is my first grow and like you i'm tired of paying a lot of money to idiots for crap stuff. I wanted to keep the costs down as much as possible but still do it right, and i reckon i've done the minimum (including nutrients, max/min thermometer, moisture tester and PH kit!!!) but it's getting silly now! I'd better get a good yield to cover what I would have spent on weed in the next few months! At least i've got all the kit for the future i suppose!

Best of luck with your grow dude, i'm only germinating tomorrow but fingers crossed for you for a relatively pain free few months!

Im using a 600w because my 1000w is too much heat in a 4x4x6.5 area