watts per gallon????????


New member
Can some one please give me the best watts per gallon for my new reef setup. I have looked all over the net and get different answers all the time. My tank is 39Lx21Dx27H inches. I only have soft corals in there at the moment and 1 Montipora and all is ok but I would like to keep a selection of Acropora. Currently my lighting is 1x150watt halide from my old tank and 2 power compacts for Blues.

As always guys, Thanks


New member
what I have heard is about 5-7 watts per gallon but as long as your getting good coverage on the bottom use what works


Team RC member
Team RC
watts per gallon is not meaningful. As I answered in your other thread it is depth of the tank that counts.


New member
Looks like you have a custom tank being 39", and it may be hard finding a fixture b/c most are 36" or 48" long. I would probably just go with pair independent 250 MH fixtures to enable me to keep anything at all levels of the tank being 27" deep. There is an article in the last RK magazine on lighting.


New member
At 27" deep I would go with 2 - 400w bulbs. Possibly 2 Lumenbrite or Lumenarc reflectors with Radium 20k bulbs. Using these bulbs would eliminate the need for actinic supplements, they have a nice color and good par. You should be able to keep any acros you want anywhere in the tank.


New member
You could use a 250 times 2 system but you would not be able to keep anything on the bottom except very low light corals.
If you are alright with that then go for it. Even with 400 36in is deep and would not work for everything....


New member
If you are willing to keep the acros and other SPS in the upper half of the tank, 250's would be fine. Maybe some softies towards the bottom.


New member
What about a T5HO hanging fixture? I've got a 6x 39W retro over my 65 (23" tall) and I've kept acros on the bottom without a problem.
Less energy and bulb replacement costs, also.

The Grim Reefer

Ready for some NOBALL!!!
A 6 lamp ATI T5 fixture would work. a 2x250 Halide system will give you plenty of light for a 27" tall, just don't get the cheap stuff with crappy reflectors.


New member
for a tank taht is only 21 inches deep i would go with the reef optix 3 reflextors, they will cover the spread fine and work well on the depth of the tank. i would use 250 watts, a friend runs 2 on 250's SE on a 120 and has no issues growing sps anywhere in the tank.