Completely enclosed hood.... air exchange?

[ScottWV1]

Hey Gang,

Am I setting myself up for trouble with a hood that is completely closed? I have a sump, but it will also be completely enclosed.

I don't plan to have a glass cover completely covering the tank, but since the hood is fully enclosed, I guess this isn't much different that having the a full glass cover...? The hood is roughly 6" tall and I have no plans to add any air stones to the setup...

If heat becomes a problem, my only choice will be to add a fan and a vent. I could open up a 2" slot in the back of the hood running the length of the tank, but that will basically be slap up against the wall, so I don't see any real air exchange happening there... (can't move the tank away from the wall because I need all the room possible infront of the tank and I specifically designed the entire system so the tank could sit flush to the wall...

I don't want to add the fan/vent unless absolutely necessary because I don't want the holes in my hood because I'd prefer for no light to project into the room (other than the light 'in' the tank). I will be lighting 24/7 on the sump/refugium which is also under the hood, so if I have a fan & vent holes in the hood, light will project out of the hood even at night...

Thx,
Scott

[Rin]

If you are going to a reef setup, you may have problems. What are your lighting specs? how big is the tank? how big is the refuge? how big is the sump? All these things will effect how much your tank will heat up.

My 75 gal system is also completely enclosed--except for 2 4" fans in the hood. With the fans my water only gets to 82 on a warm day. Light spilling out isn't really all that bad. I have 4 x 110 VHOs and 2 x 250 MHs with a 55 PC in the refuge.

[organicreefer]

what kind of lights-halides no way,vho-maybe
also yopu say youre refuge will be in youre hood lit 24/7-wont that also light youre tank?

[eses]

Having your tank up against, or real close to a wall will hamper it's ability to get rid of heat in general too. It will be harder to cool your tank in the summer unless you have air conditioning.

I think you are asking for trouble not ventilating your hood. Not only will it get hot inside it, but your also going to have an abundance of condensation built up inside each morning. You'll end up with crusty water all over your bulbs, and anywhere else that isn't water tight.

Also with your refugium, is it possible for you to move it to your sump? I know there is thought that the pump will munch some of the pods, but it may cut down on heat and light leakage.

[ScottWV1]

Here is more detail:

The lighting for the display tank will be 2 36" 110 VHOs (one actinic, one aquasun). The tank is a standard 55gal with a black acrylic divider ~ 12" in from one side.. that side is the sump/refugium. The filtration is a basic miracle mud setup with calurpa.. lighting is LOA 65w.

gotta go.. I'll provide more later... if needed

Scott

[ScottWV1]

eses - never thought of moisture issues due to the hood being 'sealed'... that's a very good point. before I move it out from the wall I'll have to put a fan in the hood - the room in front of the tank is that limited.

Thx,
scott

[eses]

Yeah, the moisture is a pretty big deal. I hadn't thought of it when I bought my hood, mine isn't fully enclosed, the back is open, and without fans the entire inside of my lid is covered in large water drops.

Is the tank running yet?

If not, do some experimenting now while it is easy. Run the lights for a couple of hours and see how hot the inside of the hood gets, I would keep it under 90 degrees F at least. You may only need one fan with that lighting, but I still think a fan would be in your best interest.

Light leakage through a fan isn't too bad, if you've got the room you can always put some kind of shroud over the fan intake too so that it draws down. It will cut your air flow some, but it will help with light leakage. The two exhaust fans on my 75 gallon have a 90 degree angle vent that points down, I made it out of sheet metal, and very little light leaks out; all that does goes down towards the back of the tank.

[ScottWV1]

eses - thanks again for the reply...

The tank is not yet running (still staining and sealing the cabinet/hood). So in your tank, although you have 2 fans plus an opening in the back of your tank, you still have a large amt of water inside your lid each morning? I assume you do not run your fans when the lights are off (or atleast not 24/7)... right?

I'm now thinking that I'd be better off with a fan plus a vent opening and simply deal with the light seepage issue...

fan/vent placement:
my tank will butt up into a corner (back against one wall, right side of tank [side with the sump] against another wall). I could put the vent opening on the left side of the hood with a decorative cover and/or possibly a decorative deflector, and put the fan in the top of the hood on the far right side pointing up.
That would draw air across the lights and the water surface and then up towards the ceiling.

What do you think? Do you know of any QUIET, Inexpensive fans?

[ScottWV1]

I guess I will have to switch the direction of the fan - as i've seen many posts saying that the fan should blow into the hood to reduce the corrosion effect on the fan.... I kind of hate that because blowing up and out seemed right since heat rises and a fan mounted in the top of a hood would work well with pulling hot air out and up...

Oh well,
scott

[eses]

I have two four inch variable speed fans (Ice Cap, $59.95 at petwarehouse.com) I run them 24/7. They are quiet, and they can draw up to 90-100 cfm I think. You can't really tell that they are on. When the temperature in the hood gets high, they speed up and at full tilt you can kind of hear them.

With the fans I no longer have any water, the inside of the hood and lights remain totally dry. If I didn't run the fans at night, I would get condensation. I have both of my fans blowing in from the back, drawing cool air from between the tank and the wall and forcing it in.

My tank setup is similar to yours, I have the back and right side against a wall. I just left enough room in the back for my hang on overflow, which gives me more than enough room for the fans.

The way mine is setup, is I have an open back on the canopy, my MH lights are mounted perpendicular with spider light reflectors. I have my fans mounted towards the inside edge of the lights, blowing in. The front leading edge of my canopy, where it meets up with the top of my tank, has a 1/2" deep knotch, running 45" down the front board that meets the tank. Basically the front board only touches the front of the tank in the corners. This way cool air comes in the back, and much of it is blown through the front of the canopy. The ambient temperature with two MH bulbs is 82-84 degrees F after they have been running about 8 hours.

I don't have any light leaking out the front vent, and on the back of the hood I have aluminum foil taped over the open back of the canopy, over the fans and everything. have it pulled away from the bottom edge of the hood about 2", so it is at about a 45 degree angle from the top-back of the hood. I don't have any light that goes up the back wall, it all goes down and floods behind the tank. I have a molded piece of wood running from the wall to the left side of the tank that is the same color of the stand so you can't see behind the stand at all.

I have lots of light leakage behind the stand, but you can't see any of it from the room the tank is in at all unless you look behind the tank on a stool.

Hopefully that was clear enough to give you some ideas.

[ScottWV1]

Thanks for the detailed description of your setup! It really helps me get a feel for what I need to do. I like the idea of the vent out the front - wish I'd given that more thought before I designed the hood I think I will probably go with the IceCaps fan since it is so quiet - I can't stand major trickling water sounds, etc... I could probably tolerate a fan more if it was on 24/7 rather than kicking on and off every little bit.

Oh well, I will put it all together and figure this part out during the cycling process.

Thx again for your help (to everyone that responded!),
Scott