Halide height

ctkecth

Member
Seeing as my real question was a bit buried in my original posting:
I am suspending my new metal halides from the ceiling- How far off the tank can they be and still be effective- what is the optimal height?
 

phixer

Active Member
He's right, and if its an acrylic tank keep your MH lights far enough away from the top to prevent the heat from warping and weakening the acrylic over time. This is a major cause of acrylic tank failure.
 

saltfan

Active Member
Originally Posted by ReefNut
8" to 10" off the water is about where you will want to be.
Even if he's running 150wMH on a 150g tall?
 

murph145

Active Member
well if hes got a 150 tall he should be running 150's more like 250s or even 400's if he wants to keep sps and clams
 

reefnut

Active Member
Originally Posted by SaltFan
Even if he's running 150wMH on a 150g tall?
Yep, & ditto to murph's comments.
 

murph145

Active Member
ur fine listen to reefnut and put them about 8-10"s off the surface i have mine 8" off the waters suraface
and the 150's will do u just fine
 

ctkecth

Member
Thanks Murph, I read or heard that you should not have any kind of cover over the water's surface when running MH- True or False?
 

saltfan

Active Member
Originally Posted by ReefNut
Yep, & ditto to murph's comments.
Sorry, I guess I should state my point instead of making you guess. Reef, you just gave out an answer without knowing the tank size or depth. That is why I threw out what I did at you. I wanted to know what type of light and how deep the tank was before giving any advice. On the terms that I threw at you, he should not have 150w 8 to 10" off a tall tank.
 

jasenhicks

Member
True, halides are a b1tch for heat. I got up to 90 with my 2X250s on my 75. And that was with the glass tops, with them off it only got to 86. With the chiller it hangs out at 78. I build my canopy completely enclosed, no open back, and 2 fans (one in and one out) if you are doing pendants or a hanging fixture its going to be less severe than mine, but with the tops heat will get trapped in pretty bad, and cause temps to rise too high.
 

murph145

Active Member
yeah mine is open top too cuz they do produce alotta heat plus u need the carbon dioxide and oxygen exchange it helps to have it open
i keep a fan in the back blowing across my lights cuz it does get hot too this way right now my chiller doesnt even come on at all right now and my tank stays at 79
i have an open top and back though so it lets the heat get out easier with the fan
i have the fan timed to come on with the lights
 

washowi

Member
It depends on what your are trying to grow? Light spectrum is very tricky, You will loose 50% of the lights PAR in the 1st 6" of the water column. So if you are hanging them that high and still have to penetrate 18" of water. Very little usuable light spectrum will be left at that depth.
Do you have the ability to use a PAR meter? That the way to really set your light height.
SPS will be difficult on the bottom half of the tank I would bet. I say this based on experience with 150's. Nothing would color up, grow, or even polyp out on my 90. Went to 400's and can't stop the growing now.
I have my light about 4 to 5 inches off the water.
Todd
 

fishy7

Active Member
I run 3 150w hqi's and 4 96w pc's and keep them at 6 inches. I have glass tops. Now my temp will go from 80 to 81 by the end of the light cycle. I run my mh for 8 hours.
I have a fully enclosed canopy and run 4 4" fans drawing the heat out and 1 fan on the sump. The temp is in check.... Not sure where I am on the light spectrum? Might want to check into this at some point.
Good luck.
 
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