New techniques? Looking for better ways to improve yeild

Well I just did my first grow and I only got about 1.8 oz from 3 plants in 3 gallon containers under a 400 watt hps light in a 2'x3' grow room.

I was wondering what techniques I could use to improve me yeild? I'm not to up to date on new techniques or trends that are showing promise. If we could make a list i'd greatly appreciate it .

AS of lately I have been seeing a lot on flowering under t5 with the warm spectrum bulbs, I was surprised to see how much people are yielding off those. And it seems to make sense because the light is distributed better, I even recently saw someone who had hung his t5 vertically and had a few t5 setups going vertically and his plants seemed to really be doing swell under those lights.

Do I need to convert to t5's for flowering or is there some insight I could use to get better yields with my 400 watt hps?

You should be able to pull really nice yields using a 400 watt HPS. I get 6 -8 ounces from 320 Watts of LED per grow, depending on strain and veg time. I grow using Deep Water Culture because I wanted the biggest yield possible for a small closet stealth grow. I use Advanced Nutrients Sensi Bloom/Grow, Superthrive(during veg), Big Bud, Hygrozyme, and Sugar Daddy/Bud Candy. I top, FIM, SCROG, and use LST while giving the plants a least 4 weeks of veg time. I grow in a 2'x2'x5' tent. Canopy management is also key to maximizing your yield.

Once you get your setup dialed in, you should easily yield more than I do with your 400 watt HPS. I'm still getting a little more out of each grow than I did the one before. I've done 6 now.

I do soil under 330w cmh's. I just grow Christmas tree style and super cropping. I have the vertical space. Ive done main lining, lst, topping, etc...... I get best yields from christams tree style in 7 gals. 4-5 zips each. I go back and forth.. with lst you have to veg for 2-3 times longer. I do living orgaincs. I just use crab / shrimp meal, neem meal, kelp meal, basalt rock dust, vermicompost / compost /worm castings.. pro mix soil. If you have height restrictions. Lst would be the way to go. Low stress training. Just tying down the plant and all the branches as they grow out. It produces multiple tops with an even canopy. To match yields. Christams tree style. I veg for 6-8 weeks or til they are 3 feet tall.. Lst I veg for 3 - 4 months depending on strain. Or til they reach 3 feet tall too.

best way to yield is genetics and extra lights