Ok, first off forget about the18/6 light cycle keep it on 24 hours, the plant dosent need rest if all the nutrients are supplyed to it without running out.

You dont want to switch to 12/12 light untill you are ready to bud/flower the plant, never do this untill the plant is large enought o be harvested.

You can use the HPS just dont have it too close to the plants , it will burn them up!

If you want to get the "maximum Yield" you should let your plant grow as large as you can contain it, 4 weeks is not enough time in Veg state to get the best amount of buds. you should let it grow for 2 monthes at least to get any good amount off it, if you try to Flower the cannabis too soon you will not get very many buds., they will be small and far and few between you might get a few joints thats it lol

as far as the hydro nutes go, follow the directions on the bottle,you definantly do not need to change it every week thats crazey, if for some odd reson it says that i would consider going to buy some better nutes lol. every few monthes 2 or 3.

Keep it on the floor, its going to be pretty heavy when full of water. what if it fell over and smashed your plants? or whatever you had it on broke? think about this stuff, A good start would be checking out some Hydroponic grow guides, or watch Mr. Greens Video "I Grow Cronic" a link to it is on the Hydro Messages Board and also on YouTube.com.
BONG0 Reviewed by BONG0 on . If young seedlings are Raised under 110 watts of flouresent grow tubes ,How long should they be under this light for before they are put under a 400 watt hps? The plants in question are femminised white widow and are about 2 inch tall now and have been growing quickly for three days under this light on 16/8 do you grow them for four weeks like this and then put them under the hps bulb straight on 12/12 or do you let them grow so big and then put them under the hps for 18/6 for four weeks?:confused: This Rating: 5