Height and spacing recommendations - 2x Prime 16HD's over 12" x 24" footprint

[Koleswrath]

Hi folks, I'm throwing out a hail mary here and hoping someone has this setup and has some PAR measurements to go along with it. I'm upgrading from a 12 x 12 x 12 (ish) cube which BRS provided measurements for making it easy to get a starting point without buying a meter. 

My new tank is ~12"x 24"x 14" deep so I picked up another 16HD but I'm not sure the best height and spacing (and spectrum/intensity settings) for two of them over this footprint.

 

I've searched the Prime Facebook page but didn't come up with anything and my posts have been pending approval for 2 weeks....😒

 

Let me know if you can help!

Thanks
 

[mcarroll]

Well, depth of the new tank is practically the same as the old tank.  So your new light settings could be just about identical to your old setup.   No change would probably be OK.

 

The new tank also  has a similar light:area ratio – 1 sq ft per Prime.  So if you liked your old setup, the same mounting height should also work with two lights on your new setup.

 

BTW, is 100% of that surface area "display area", or is this a tank where some of that area is a filter compartment?  You'll want to mount lights relatively lower to avoid lighting the filter area, if present.  A rule of thumb for lights with ~90º lenses is that mounting height should be 1/2 of the shortest side of the area being lit (6" in both of your cases), then customize to your tastes from there.  We can calculate for other lens angles too.

 

Last thought:  An inexpensive lux meter can help a lot with lighting setup – it's accurate enough and will give you objective repeatable measurements.  Much better than copying a setup off the internet and praying.  👍   Keep in mind that although it is somewhat more accurate, there's no need to measure in PAR units just to accomplish what we're doing with light setup.   If you had to (or wanted to) make any more significant lighting changes than you are, a lux meter would be REALLY handy for "copying" the output levels on the old tank – as seen from the water surface by the meter – over to your new system.  Lux meters are also CHEAP.  $10-$20....sometimes less.  (Lux meter apps are $free, but can be finicky.)  Also, you can always convert from lux to PAR with a common conversion factor approximation like 60 (sunlight is 50), if you find a need to use PAR units.  If you can get access to a PAR meter, you can even make a 100% accurate conversion factor for your setup to use with future lux meter readings.

 

2¢