4' tank distance between BBs?

[AbjectMaelstroM]

Those of you running multiple Black Boxes (vipar/Mars) how far apart do you have your fixtures?

Right night I'm trying to hang two of them over my 4' 120g. As it stands there's 12" between the two fixtures and there is 2 inches on either outer edge of the fixture and the side rim of the tank.

Should I bring them in about 2 inches each? More? Trying to nail down the lateral placement now because it will be more difficult to do once tank is set.

PS. I replaced the inner lenses to 120s, outer ring is 90s. Lights are ~12" off the waterline (to be).

 

[Big G]

Boxes/light fixtures will vary considerably depending on the emitters installed. So instead of guessing about the ideal coverage from your lights, consider getting one of these. Way cheaper than a PAR meter, but will give you basic info that will help you.

 

[oreo54]

@ 12" up your cone spread at the water line on the outer 90's is 24"..
Inner are a diameter of 42"...(120's)

so figure "adding" 12" radius on the outside ring.. 21" on the inside ring..

21" will overshoot the outside since there is only about an inch or 2 difference in diode centers.

first suggestion is to ignore the outers and concentrate on inner diode spread..

External box is 16x8
Inner diodes are approx (eyeball) 2" from the perimeter..making a rectangle of about 14x 6 (best you measure them)
10x2....
Spread will be 34X26....(ignoring the 90's)
22" for tank outer edge to box edge each side, so lights should be "bumped" pretty close together.. like touching..
Check here:

LED Lighting Beam Angle Calculator

A simple calculator that determines spot size by a light's beam angle

store.marinebeam.com

you can dry test the lights w/ a white sheet and the light 12" from the surface..



'

 

[AbjectMaelstroM]

Yeah... Had to bring them in 4" each. Only 4" apart now. Did the paper trick...did the trick, lol. Was always a visual learner.