Lighting for Chaeto

[Original Fin]

One question I wanted to throw out there: How much and what type of lighting would be appropriate to encourage rapid chaeto growth/nutrient export? I have an 18" T8 flourescent hood that fits perfectly over my fuge area, but it's only rated at 15 watts. By utilizing this fixture and painting the fuge walls, I can easily keep light out of other areas of the sump where I don't want nuisance algae to form.
Considering we're only talking about 3 gallons of volume in which to grow the chaeto, will 15 watts be enough to get the job done?

[Ninong]

Considering we're only talking about 3 gallons of volume in which to grow the chaeto, will 15 watts be enough to get the job done?

The volume of water is totally irrelevant. The chaeto doesn't care if it's in 3 gallons or 300 gallons; all it cares about is the amount of light and the quality of the light that it actually receives. The same goes for corals. An SPS coral that requires a lot of light isn't going to be pleased if the aquarium owner tries to tell it that it should be happy because it's getting 6 watts per gallon when what it's getting is two 15w NO fluorescent tubes over a 5-gal nano tank. It would be so much happier getting 2 watts per gallon sitting 10" below the surface directly under a 250w metal halide lamp in a 120-gal tank.

So forget about watts per gallon. That's a really dumb rule of thumb that was invented by lazy LFS owners decades ago. It was only intended as way to explain things to brand new potential reef aquarium owners who had no idea whatsoever what they were doing. It may be somewhat applicable to typical 75-gallon mixed-reef aquariums but certainly does not hold water when it comes to smaller tanks.

I would recommend that you consider at least 60 watts of fluorescent lighting in the daylight spectrum to light macroalgae even if it's only a 3-gal volume. You want the chaeto to grow fast enough so that you can prune it every other week. You won't get much nutrient export from chaeto in a 3-gal volume of water but it's certainly a good idea that will give you valuable experience for when you move up to a larger system with a much larger space for chaeto.

[Original Fin]

I would recommend that you consider at least 60 watts of fluorescent lighting in the daylight spectrum to light macroalgae even if it's only a 3-gal volume. You want the chaeto to grow fast enough so that you can prune it every other week. You won't get much nutrient export from chaeto in a 3-gal volume of water but it's certainly a good idea that will give you valuable experience for when you move up to a larger system with a much larger space for chaeto.

Thanks Ninong.

I should be able to retro the fixture I like for higher output tubes, or what do you think of standard residential use CFL's?
I'm still working out the design of my WIP sump/fuge, but I've got it nailed down to using two 10 gallon tanks connected by bulhead fitting. I'd be hard pressed to get any more volume than that squeezed under my 55 stand without breaking the whole thing down. Of course a good chunk of the available sump volume is needed for skimming and return, but I can dedicate 4 more gallons to macro if you think that would make much of a difference to a 55 mixed reef?

In my current design, I have the afore mentioned 3 gallon fuge in the first 10g, and then I have another fuge chamber and return section in the 2nd 10G. I was loosely planning to use the second fuge area for non-photosynthetic bio filtering...probably just a DSB and/or LR. Would it be more beneficial to my system to use this second area for macro as well? The combined fuge area volume is roughly 7 gallons, and that already accounts for the displacement of a 4" DSB. If it weren't for the DSB, total fuge area would be closer to 10 gals, but I really don't want to compromise on the DSB. The sand bed in my DT is kind of in no-mans land, averaging about 2 & 1/2 " deep, so I feel the remote DSB is a must have.