Venting UNDER the grow room...

A buddy and I are running a 400w mh/hps along with some supplemental cfls in his shed beside his house( 12 by 10' ) . I don't know if the venting is really need, but we agreed on cutting a whole in his shed floor, running the ducting through the whole under the shed ( it's a pier and beam shed obviously ). Considering even putting a 10 -20 gall bucket in the ground filled with water. Then the exhausting duct secured to the bottom of the bucket venting the hot air from my cool tube. Leaving no heat trace.. Hopefully. For smell we will have a filter on the intake before the cool tube. Anyone see any problems with that?

Peace in the Middle East...

I did something like that, buried the pipe in the ground though. Without a lot of mass to absorb heat you probably won't get much cooling effect from it(especially if its just thinwall tube exposed to air, you'd have to run a LOT of it then).

My room is in a basement, the floor was exposed to the dirt(the rest of the basement has a poured floor, really weird) and before installing a subfloor I buried about 80' of 4" thinwall drainage pipe under the ground, about 30feet of it is at least 2 feet down, the other 50 feet is just 6' under the ground, snakes around the whole room.

But my room is sealed, the pipe runs into the veg room, underground, and runs back into the flower room(one big room sealed up nice with a crappy little wall splitting them), the air never goes outside.

I don't know if if you'd be able to exhaust the air slow enough(or diffuse it into the water enough) for it to cool down before leaving the bucket, the air would probably have to be going so slow it wouldn't be en effective exhaust. Maybe just spiral about 60 feet of exhaust ducting around the bottom of the shed and it'd cool off a good deal before leaving the ducting, but if you are worried about a heat signature the bottom of his shed is gonna light up on FLIR if you don't insulate it also, and the tigher you try to insulate it the brighter the spots you miss shine.

I was planning on haveing a skirting around it. With radiant barrier on the inside of it. I'm guessing the next best is to bring sewer over to the shed. Tie the 6" vent to the 4" sewer line and insulate the hell out of it.

Blowing air into a sewer line is gonna cause trouble. And I don't follow your exhaust into a bucket of water idea. The air has to GO somewhere. Is your concern heat signature? There's easier ways to cool the exhaust.

Yes, I would like a low heat signature. With the bucket of water i was going to secure the end of the ducting in the bottom of the bucket then fill it with and make it my exaust. Hoping the air coming through the water would cool it off some what. I know it would be huge bubbles more than anything, but hopping that cool water would help with some of the heat. Im open to suggestions.. Just brain storming still..

Friend said I don't even need to vent, Id say he's had one to many puff's..

Simply dumping into a bucket will, as you or someone else said, just result in large bubbles doing little for cooling. You'd have to force the air through a PVC diffuser or something which would create huge backpressure and then require a stronger fan. There's easier ways to cool the exhaust air.