how far should mh be from surface of water?

[deepreeftank]

any help will be app.

 

[danmhippo]

about a foot. More, you are wasting intensity. Less, you are running risk of water splash and bulb cracks.

 

[Jefe12234]

Mine is about 8 inches from the water and this seems to work well so far. It's only been up a couple weeks though, so I'll have to see how it works in the long run (salt spray, heat in the summer, etc).

 

[gbtower]

As close as you can get it without causing heat problems.

FWIW, I keep mine about 10 inches off.

 

[ScottJ]

I have a older model Hamilton dual 175 MH that came with a plexiglass insert that is several inches lower than the bulbs and it keeps water/salt spray off of the bulbs. It does get salt build up so I try to clean it every other week or so. If this setup, I let the unit rest directly on the top of my 72G. Fans and a ceiling fan keep the heat from being too much. My question - Should I remove the plex and raise my lights several inches???

thanks for the help,

scott