is 12" too tall for vho canopy?

[sls]

im building my new canopy that ive been putting off forever. i was thinking going 12" high with it. so the bulbs will probably be sitting in the area aroun maybe 10 off the surface of the water. is this going to be too high for vho? im going with 220w on a 55gal and will be adding another 220w probably next month.

[SPC]

IMO yes. My VHO canopy is about 6" high and is only thid high because of the Sea Swirls in the back.
Steve

[chem-e]

My canopy was only about 4-5 inches high when I was using VHOs and I thougth that it worked out pretty well. Any higher, I would think that you'd lose quite a bit of intensity.

[sls]

well then maybe ill use 9" sides which would actually leave the bulbs about 6" from the water and do a fully opening top instead of 2 doors in the front like my original plan. i mean i guess i could lay the bulbs right on the tank but that would be a pita to keep moving them when my hands would be going in the tank which is everyday. any ideas?

[ousnakebyte]

Well, if you ever decide to go MH, then believe me, you'll want that tall canopy. I know I said I would NEVER go MH, and now here I sit, three years later with a new canopy b/c my original was too short. It is, by the way, supplemented with two VHOs.

It's something to consider anyway...

[MarksReef]

I agree. Only build 1 canopy incase you do M.H.'s.
just put blocks on the insides of the canopy to mount your VHO's then if you switch to MH's all you have to do is remove the 2 middle ones.
Here is a pic of mine w/ the blocks to mount the VHO's
http://reefcentral.com/gallery/showphoto.php?photo=16872&papass=&sort=1&thecat=3265

[JRoweNole]

Go with the higher canopy for possible MH.

I supplement VHO's with my 250 watt, 10K MH. I got my VHO's closer to the water surface by suspending the bulbs from each end cap with plastic ties that loop through a plastic tie fastener attached to the roof of my hood.

[quazi]

I built my canopy so the end caps can sit on top of the aquarium frame. This is OK for a glass tank. Now my canopy is just a cover for the tank.

[XxDutchxX]

I would keep the high canopy and get some MH. But I would mount the VHO lower in the canopy.

[SPC]

Originally posted by sls
well then maybe ill use 9" sides which would actually leave the bulbs about 6" from the water and do a fully opening top instead of 2 doors in the front like my original plan. i mean i guess i could lay the bulbs right on the tank but that would be a pita to keep moving them when my hands would be going in the tank which is everyday. any ideas?

Hmmm, let me try and clarify the way I have my VHO's mounted.

First of all my canopy, hood etc... was built for VHO only for a reason, I don't like the looks of those tall canopies and don't need one with a VHO only set up. My VHO canopy is built from stock lumber and is all 1x6's so only cross cutting is needed. I think it took me about 3 hours to build, and I probably have about $20 in it.

My 180 is 24" wide, so I made the canopy 18" wide to allow me to have about a 3" space at all times between the front tank frame and the canopy. When I need to stick my arm in the tank for maintenance, I simply push the canopy back giving me 6 or so inches to do my work. The length of my tank is 6', so the length of my canopy is 6' - 2". The top of the canopy is built with three 1x6"s which leaves a space in between each board for ventilation.

If I would have originally built my canopy with the thoughts that I may go with metal halides in the future, then I would now be building another metal halide canopy anyway sense I am setting up an 8' tank later this year.
Steve

[dnjan]

Originally posted by chem-e
My canopy was only about 4-5 inches high when I was using VHOs and I thougth that it worked out pretty well. Any higher, I would think that you'd lose quite a bit of intensity.
Could you explain why you would lose a lot of intensity if the canopy is more than 4-5 inches high?

[chem-e]

I think (and I may be wrong) that in general, flourescent bulbs lose intensity as their distance increases. For example, I have T5 bulbs also and one of the cons to T5 bulbs is their ability to penetrate to the bottom of the tank, which is why some people mount their light-loving-corals towards the top of the tank. Well, if this is true for VHOs too, then I would assume that you'd be losing light intensity the farther you mount your bulbs. :confused:

Hopefully this answers your question.

[sls]

i was originally going to use the blocks to lower the vhos like in the pics above but then how am i going to get my arm in the tank to do periodically clean feed, clean the glass etc... maybe ill attach them to a shelf on hinges so after i open the doors i can raise the shelf to a 45 degree angle allowing me access. then if i go withg halides in the future it will only need slight modifications. im starting to make this harder than it needs to be i know it!:lol:

[dnjan]

Originally posted by chem-e
I think (and I may be wrong) that in general, flourescent bulbs lose intensity as their distance increases. For example, I have T5 bulbs also and one of the cons to T5 bulbs is their ability to penetrate to the bottom of the tank, which is why some people mount their light-loving-corals towards the top of the tank. Well, if this is true for VHOs too, then I would assume that you'd be losing light intensity the farther you mount your bulbs. :confused:

Hopefully this answers your question.
The loss of intensity is significantly greater for light travelling through our tank water than for light travelling from the flourescent bulb to the water surface. Distance above the water has almost no effect for reasonable hood heights.

On the other hand, salt accumulation on the bulbs can significantly reduce light output, so either cleaning the bulbs regularly, or having them high enough so they don't get accumulations makes sense.

Also, heat absorption (the water absorbing heat from the bulbs) is sensitive to distance from the bulb to the water surface. In some cases, this can be an important consideration.

[MarksReef]

Originally posted by sls
i was originally going to use the blocks to lower the vhos like in the pics above but then how am i going to get my arm in the tank to do periodically clean feed, clean the glass etc...
I was wondering the same when I did mine. Think of it this way. The light close to the front of the tank wont be right up against it, It has to be a little farther away to direct light from both sides of the bulb. It looks closer then it is So I took a better angle shot for ya.http://home.rochester.rr.com/marksreef/new/HAND2.jpg

[sls]

how manby inches are your vhos from the water? looks like maybe 7-8 inches? see, i have a 55 which is only 12" front to back so my bulbs are going to be really crammed in there so the first one is going to be right up against the door. i guess when i get the shell built i can decide after i look at the bulb placement what ill have to do then and plan accordingly. thanks for all the input.:D