Distance to the surface...

[pablodub01]

Hi All...

I just bought and Arcadia 3 series pendant with a single 150W MH and 2x15w T8's actinics for my 50G corner tank.

My question is... how far from the water surface should i install the lights?...

Cheers
Pablo

[papagimp]

as close as you can get em. 3-4" would be good I'd imagine. Any other thoughts?

[an411]

Mine are about 4 inches and have been fine

[ReefEnabler]

I'm curious about this too (asked about the it in a clam thread).

I'll have 3x250w MH PFO, and 2x160w VHO actinic

my tank builder (AFY) recommended putting the lights 12" above water since they put out so much heat. Will that cause too much light to be lost?

[rustybucket145]

Heat's gonna be you enemy when placing lights so close to the water. You get pretty much the same amount of light when the lights are 8"-12" above the water. This space allows the heat to dissipate instead of cooking your tank.

[pablodub01]

Good.... so maybe a middle term like 6" or 7" will be fine?

[ReefEnabler]

out of curiosity, whats the dimensions of your 50G corner?

[der_wille_zur_macht]

Many people quote distances without consideration for exactly what they're measuring. Are people describing distance from the top of the water to the bottom of the fixture, or distance to the bulb itself?

The most common rule of thumb for MH fixtures is to have the bulb about 8 - 10" off the surface of the water. That might mean that the bottom of your fixture is 3 - 4" off the water. I wouldn't put it much closer than that for fear of poor light spread and restricting access into the tank.

I wouldn't put it much higher either, without good reason - as you raise the bulb, intensity drops off very quickly - as the square of the difference in distance. So raising the fixture from 10" to 12" is much more of a drop than from 8" to 10".

[ReefEnabler]

That raises a good question that I can't answer just yet :)

I'm still waiting on the 'detail plans' for my tank and stand/canopy from AFY, all I know is that the hood is being made 14" so that the lights can be mounted 12" above the water. I need to double check with them if this means the BACK of the pendant is 12" above, or the actual fixture is at 12".

I will be using a lux meter, so I'm guessing it won't be difficult at all for me to make small adjustments on my own if need be, possibly by just using wood sheets as a spacer.

[pablodub01]

<a href=showthread.php?s=&postid=11006068#post11006068 target=_blank>Originally posted</a> by RyanBrucks
out of curiosity, whats the dimensions of your 50G corner?

It's a Trigon 190
http://www.juwel-aquarium.de/en/trigon.htm

And I'm talking about the distance from the bulb to the surface of the water.

Pablo