How height the MH light should be?

[lastduke]

I am going to put 150W MH on top of 29G nano with 20G sump system. How high I should go for this lihgt?

 

[heller792]

I was told 20cm but I have mine as low as possible and keep a fan blowing across the underside of it

 

[tanker]

I have 150w bulb and they are only 4 inches above the water. Been that way for years.

 

[lastduke]

tanker, how much volumn your system is? do you have chiller?

Heller, are you using only one fan or two fan one for in and one for out?

 

[tanker]

<a href=showthread.php?s=&postid=13081595#post13081595 target=_blank>Originally posted</a> by lastduke
tanker, how much volumn your system is? do you have chiller?

120 tank, about 20 gal sump. I have fans only in the sump. No chiller.

 

[lastduke]

yes that is why you don't have the problem, what I have is only 30Gwith 20G sump, I may have the heat problem......

 

[serolis7]

A 400W and 175W six inches above waterline. No chiller. No heat problem. I will be raising my lights a couple of inches to prevent salt from encrusting on the bulbs.

 

[heller792]

I only have 1 fan. just a cheap clip fan and that pushes the warm air away from the water, It works fine for me. My tank is constantly 79-80, without the fan it goes to 85 over 8 hours but it does depend on the humidity and temperature that day.

 

[lastduke]

I am making the canopy to hang 150W MH about around 10 inch about water surface. I am going to cut two holes on top of the canopy, one blows the air from top to the water surface and another pull the air out. I can't install the fans at side because I am going to use the glass to make the four sides.

my question, two fan's on 30G will make a lot of vaporation, does it make any problem to the water parameter? I do have the ATO.