Lighting suggestions

[tomanero]

I've got a new (to me) 72x18x18 tank.
(I've seen this tank sized from 86g to 125g depending on who's list I check it against. Calculators seem to figure ~100g so I'll go with that)

Was interested in lighting suggestions (in regard to MH's)
Actinics will be 384 Watts, 4x96W PC's (since they came with the tank).
Planning on keeping sps, lps, softies, etc.

Thanks in advance for your input.

[don-n-sa]

yes the calculators are right...the formula is L x W x H divided by 231.

72x18x18 is 101 gal, however measuring the Inside dimensions would be more accurate.

Halides for a 6ft tank that is 18" deep, there are alot of members here that can help you more, but I would think 3 x 250w would be plenty for just about anything.

[tomanero]

Is 3x250 to much though?
Would I be better off with 2x250 or 3x175 since the tanks only 18" deep?
I know the sps's would love it but would the 3x250's be to much for softies, etc. that don't love the light as much?

[caferacermike]

Steve I'd begin with 3x 250w. Keep in mind I have 2x 250w over a 75g which is 48x 18x18 (I think if I remember right this early). The halide rule of thumb I learned was that if measuring from the center of the bulb expect about 9" of good spread each direction, so an 18" diameter. Place the first bulb 9" on center from the edge of the tank and then 18" or less apart from there across the entire length.

I come up with 4 lamps being perfect. Now if I'm thinking correctly this early in the morning, Place the first lamp at 9"OC, 27"OC, 45"OC, and 63"OC. This would allow for 9" off one end, then 18"x18"x18" with 9" to spare on the other end. This all works out well for a 72" long tank. I'd maybe even think about getting screw in bulbs as the inensity is spread longer than a more direct firing dual end bulb. For that tank you'd want long parabolic style reflectors and the expensive Lumenarcs don't seem as though they'd help much since they are made to project over a large square.

The 18" rule was handed to me to prevent dark spots between the bulbs. To save money why not do as I plan to do with my 400g tank? Since I cannot afford to run 4x 1,000w lights to gain the same 10wpg I currently have, instead I plan to have 1 very bright area that tapers off to a more shaded area. This plan will allow me to have SPS in one corner of the tank and have plenty of areas for LPS and shrooms that prefer lower lighting. You could group up 2 or 3 250w retros in one area spaced 18" apart but have them farther from the edge of the tank and let the PC's warm those areas up with a little less intense light. Those areas will still be bright enough to look at and enjoy the LPS you place there but not as intense as the halide areas.

[tomanero]

Mikey, I like it.
The taper off idea.
Especially since there's a large glass brace across the center.
I can light one side of he brace with halides at around 12"OC then at 30"OC (using the 18" rule).
(This way the halides won't be dimmed by going through the glass brace (which I'm sure will not be crystal clear long)

Tapering may also cut down on the live rock bill (which I'm not looking forward to) since everything won't have to be so close to the surface.
It guess it could be worse.
I could have to buy enough rock for a 400g. Sheeeeesh.
It may be cheaper if we rent a boat and go chip off the rock you need ourselves when your ready. :shades

Thanks for the help.

[caferacermike]

Mikey, I like it.

Tapering may also cut down on the live rock bill (which I'm not looking forward to) since everything won't have to be so close to the surface.
It guess it could be worse.
I could have to buy enough rock for a 400g. Sheeeeesh.
It may be cheaper if we rent a boat and go chip off the rock you need ourselves when your ready. :shades

Thanks for the help.

Not to hijack but I took care of most of my rock needs on the cheap. Ed over at Wolf Reef pulled through and ordered a pallet of Fiji premium dry reef rock. It's the same stuff you pay $8 a pound for except it is white and shipped dry. Will take 6 months to seed up but for less than $2 a pound it can't be beat. Plus his average price for plain live rock is right at or less than $3 a pound. Saw a post that said he had another pallet on the way since what I left him sold the same day, hadn't seen an update as to when it was delivered. If interested I may be headed that way one night this week....