MH Hood 2x175w

[Delphinus]

Nicely done!

[kwirky]

looks real nice. is that plywood? You've got some moulding (sp?) around the edge. Would have been great to see it built with MDF or the likes.

I like the design and the way you integrated the fans to blow directly on the bulbs.

What I would do is grab some scrap alluminum and cut it to line the inner edges of the canopy to act as reflective material. I have a feeling that black paint's absorbing a lot of light from those parabolic-style reflectors.

[BlondNasoTang]

Originally Posted by kwirky

looks real nice. is that plywood? You've got some moulding (sp?) around the edge. Would have been great to see it built with MDF or the likes.

Yes it is plywood but only on the top, the frame is built with treated spruce 1''x8'' and the rim is baseboard mouldings.

This was my first hood I ever built kinda like a prototype and I learned a lot from it, the next one I build is going to be far more effeient and elaborate and I plan to build a frame with a finished MDF shell.

[Bryan]

Looks good, just a thought though, you may notice a change in the spectrum of the MH bulbs with the fans so close to the bulbs. MH's are designed to run at a optimum temperature, cooling them causes a change in performance and spectrum. You want to get rid of excess heat in the hood but without directly cooling the bulbs.

[mark]

Looks nice.

Get some details on your 'thermo-switch'.

[BlondNasoTang]

Originally Posted by mark

Looks nice.

Get some details on your 'thermo-switch'.

the Thermal switch is a PT6 Master Flow auto-adjustable thermostat i bought at Home Depot in the roofing section (A reverse thermostat). I installed it under my hood away from direct airflow and wired it up to my fans and set it up to come on when the air space under the hood is just under 78 F it works really well the fans are only on when they are needed. This cut my evaporation in half and cut down on power consumption.
My tank temp stays constant only varying from 78.2 F to 79.4 F

[BlondNasoTang]

Originally Posted by Bryan

Looks good, just a thought though, you may notice a change in the spectrum of the MH bulbs with the fans so close to the bulbs. MH's are designed to run at a optimum temperature, cooling them causes a change in performance and spectrum. You want to get rid of excess heat in the hood but without directly cooling the bulbs.

I have also read about cooling the bulbs changing the spectrum so before I installed the fans I did some majour reaserching on it and found an artical where they tested MH bulbs with and with out airflow being blown directly overthem and tested for any diffrences the conclusion was...
In order to effect the lights output the arc tube's temperature would have to be changed, and since the arc tube is running at such high temperatures, any ambient temperature variations around the outer glass are insignificant and won't change the efficiency of the bulbs.
I have the fans set up so one pulls cool air in and the other one pushes hot air out.

As for the black paint on the inside.... that was a mistake but with over 350watts over a 44gal it dosen't seem to have a big enough negitive efect to take it all apart and repaint it. I am going to be changing the reflectors soon to bigger more reflective ones soon.