GrowTutor

that's the "R" in RDWC. it's connected to my main pump in the control tub. what goes into the lid is basically a 90deg pvc elbow. the sprayer end is just a pvc end cap with about 10 small holes drilled in it. i think there is a pic previously in the journal. but it sprays really well. i read that a waterfall/sprayer is better for DO in my res vs. airstones. so i have both. 2 airstones per airpump in each tub plus the sprayer.

No, the bigger droopy one in the back-right...

gotcha. my bad. it's a 3 inch fresh air inlet. connected to a 12 v bilge blower and then the inlet is actually a bathroom exhaust fan outlet on the side of my house. not using it now. put it in for when i get the HPS running if i need to get some cooler outside air in. thought that i could run my HPS at nite (in the summer) and would have some cool nitetime air to bring in to keep temps down.

You know that if you shorten that hose and remove the sharp u-turn it'll have more airflow, right? 3" isn't much for a HPS hood anyway, most are 6-8 inches.

when i do use it, the end of it will be on the floor under the tubs. i have a 6 inch inline fan to exhaust the HPS thru a cool tube. the 3 inch is just to bring some fresh air in.

and i bought a .5A, .75A and 1.0A 120V to 12VDC transformers to control the speed of the bilge blower. just swap some wire and i have a 3 speed bilge blower

Does the 6" inline exhaust also have a 6" intake for the cool tube or are you using the intake side of the cool tube to remove the heat from the grow room? With a larger exhaust than the intake you'll end up with negative pressure, assuming that the rest of the room is fairly air tight.

If the 6" inline is on it's own air circuit the the 3" pumping air in could cause positive pressure if the room exhaust isn't as big or bigger. I actually like positive pressure for grow rooms because it helps keep the bugs out.

that part i haven't figured out yet. i was going to use the other end of the cool tube "open" when i first get the HPS going and see how it works. the room is not air tight at all so i shouldn't have to worry about the negative pressure.

just a quick update:
end of week 4 of Veg and first day of 12/12