hood fan placement

[Ah64av8tor]

I have been working on the light fixture to house 2 Icecap 250w HQI and 4 T5s powered by an Icecap 660. I used 1’ X 1/8’ angle aluminum and pop riveted the rails that the fixtures will attach to. I am incorporating cooling fans to keep the temp down. The hood will be completely open above the lights

The 2 Icecap 120mm fans that I have now have been running great for about 5 years., so its time to get some new ones I think.

My question is how should I place the fans?

Should they blow on the HQIs across the fixture?

Should they blow down toward the water surface?

Should they blow up ward away from the water surface exhausting heat from the hood?

Should they be at an angle to blow down across the lights and water surface?

__________________

 

[michaeldaly]

I would have them blow across the water. MH seem to shift colour if they are cooled.

 

[Ah64av8tor]

I didn't think it was good to blow on the MH.

Blowing up, down or at an angle works best with the current lay out, theres not enough room in the hood to get air in behind the fans on the sides unless they are under the lights creating shadows.

 

[Ah64av8tor]

Anyone?

 

[Ah64av8tor]

Bueller?

 

[Driftwood]

I have one fan blowing outward and a hole in the other side to allow air in.

I would love to know if your not supposed to blow air at a MH fixture... I am planning on adding a second fan and that one will blow in to create a tunnel effect through the canopy.

 

[Acroholic]

I have an enclosed PFO hood and have 2 fans, one blowing in and one blowing out creating a nice draft blowing across 3 400W MH's keeping the temps at a minimum.....
With an open top like yours..I would either have the fans blow across like mine or have them both directed inwards and let the hot air escape out the top.....just as long as you can direct the hot air from blowing down on your water...that wouldnt be a great idea...IMO

 

[Ah64av8tor]

The hood is only 48" and the fixture is 47 1/2 so there is no room between the fixture and the hood for the fan and I dont want to cut a hole in the wood.

 

[Jim_S]

I don't have them now, but last year when I was running a reef, I had MH retro kit. I used my fan to blow across the water and the lamps. I didn't see any change in growth or color from summer to winter (when I didn't run the fans), but I never did any tests either. It seemed to work just fine for me.

IMO, you should have either both fans sucking hot air out, or one sucking in and one pushing out.

I have seen some sweet hoods with the fans on top, pushing air out, but I don't know how well they function in that configuartion.


BTW, sweet set-up


Jim

 

[Ah64av8tor]

Ok here are some pics of the light rack.

This is the end I still have to cut and bend the arms that the T5s are on down at a 45 degree angle and cut the end panel from 3/32 T4 aluminum and pop rivet it on.

From the top # 1&3 will be 120mm fans pointed down at a 45 degree angle and #2 will be 120mm fan pointed up.

This is the only way I can see to get full coverage of the water surface and exhaust.

Comments would be good about now!

 

[Jim_S]

Looks like it would work well to me. I'd put the two outside fans sucking hot air out though. JMO.

Jim

 

[Ah64av8tor]

If I put the two outside fans blowing hot air out, then I wont get as much evaporative cooling as if I have them blowing across the water.

 

[Ah64av8tor]

I have done more reading on the subject, and am thinking that I will need more cooling of the T5 bulbs for better performance.

Getting air in to the hood should not be to much of a problem with the open top and the louvers in the doors.

Do you think this fan placement will get enough flow along the bulbs?