VHO mounting height options

[dave90ztt]

I am very limited in my canopy, only 6 1/2" of clearance from top of water to top of canopy. Is there any problem with mounting my retro vho's that close to the water? what is a good height to hang them? i can modify my canopy if i have to. My tank is 84x24x24. I plan on stocking mostly lps and a few sps, and a couple clams. Give me your opinions thanks

[jimsplace]

I think my VHO bulbs are around 6" off the water. If you mount them on your existing canopy you will be much less than that. Much closer than 6" and you will get a lot of salt on your bulbs, also more heat. You might want to consider modifying the canopy for additonal clearance.

[dave90ztt]

I understand that i will have to raise up the canopy..but how far?? what is the number i should shoot for? 10", 12" 14"?? with my tank only being 24 inches deep with a shallow sand bed i think if i get the bulbs off the water 12" i will be in good shape.

[amt68]

Dave, I had a 200gal 96*22*22 with VHO's and my hood was only 6" tall. Like Jimsplace mentioned salt spray was a issue and I did have two fans to help for cooling. But the corals did fine.

[dave90ztt]

surprised i havent gotten more feedback...i have the option to run all vhos or vho/t5's. maybe that will get a few more replies.

[houser]

I ran VHO's around 1.5" off the water for roughly 18 months with no problems. Very little salt accumulation on the bulbs - Gentle water movement and plenty of ventilation since the canopy wasn't completely enclosed. Did have to clean bulbs periodically.

[jimsplace]

With a 24" deep tank, I would shoot to keep the bulbs about 6" +/- off the water. I think if you go to much higher you might lose to much PAR. It will also depend somewhat on what kind of water turbulence you have at the surface. I have a Vortec MP40 and a K3 in my 90 with quite a bit of surface turbulence and I only have to wipe the bulbs off maybe every 1-2 months. If your water surface is fairly calm maybe you could get by with 4".

[dave90ztt]

thats kinda suprising actually. now if i were to run vho's as supplemental actinic and use t'5s for main lighting is 6 inches going to work? retro in (2) sets of 36" 5x54wt powered by icecap 660's.

[tawolcott]

Tagging along here. There has to be some recommended height although I can't find any on vendor or retailer web sites.. Minimum height/Max height etc..... general guidelines ??

More interested in t5ho

[robot2222]

the closer to the water you get woud probably be better if cooled sufficiently . one reason the 24'' inch depth the other if you go higher you will get a mirror effect . reflecting off the water back upn towards the light.