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lighting for a 20long


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How should I light my 20long (30"x12"x12"), I would like to be able to keep most any coral anywhere in the tank hears what I’ve been thinking...


1. Four 24watt HO-T5 lamps

Pros- lots of light, lasts a long time, uses little electricity, less heat, lots of options for lamps

Cons- don’t know the light spread over 30inchs, no “shimmer” effect


2. One 150watt metal halide lamp

Pros- lots of light, “Shimmer” effect, lots of options for lamps

Cons- don’t know the light spread over 30inchs, lots of heat, most electricity


3. Two 70watt metal halide lamps

Pros- lots of light, good light spread, “shimmer” effect,

Cons- heat, most expensive annual lamp replacement, not many lamps too choose form


well those are my three options, and I cant decide witch to go with, what option would you all out there go with?


the tank will be open top without a canopy, the light(s) fixtures will be hanging Above the tank


I was thinking for option 1. a SLS Tek Light, option 2. An AquaMedic pendent, option 3. Two JBJ clamp on Viper lights

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How about (4) 75 watt 30inch vho's with a workhorse ballast.Very inexpensive and great output.


I think that this would work really well for a 20L since it is such a shallow tank. Esp. since you can get the light close to the surface and the corals won't be that far from the light, giving you the option of keeping about anything you want.

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It would be a good option if they made 30" VHO's :) They only come in 2'' date=' 3', 4', 46.5', 5 and 6'. My vote is for MH with some type of lumenarc reflector to disperse the light better. Later Ryan[/quote']


aahhh...well I didn't really know the sizes of T5's.(whistle) So I guess my vote would be for dual 70w MH. I actually had a 250w MH on my old 20L, but it was up a about 8" or so from the surface and I also had 2x65w actinic. Seemed to work pretty well for me.

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Either choice listed will do GREAT on a 20 long. I have a 20L as my RBTA prop tank, and it's being lit by a 400watter right now. I have used 4 24w T5's, MH with actinic supplement, and VHO only. I think I even used PC on the tank before too.


It really depends on what you plan out to keep in the tank.


I think there are some really good 30" Fixtures with T5's. Aquatronica? I can't remember off hand, but they're a little pricey.


Prolly the best way to go would to get a canopy built, and run either retrofit VHO's or T5's or both. If going with either of those, go with a shorter canopy.

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  • 3 weeks later...

On my 20g long I have a 150w HQI and IME it does cover the area of the tank with a bit of lower light areas to the corners. Not noticable to my eye, but I can tell in photo's. JME


If I had to do it over, I would have just raised the canopy a bit more. Right now the MH is only 5" off the waters surface.


I keep T5's on my other tank, if you stack the T5's right it could work too.



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what about your budget? 2x 75W is nearly double the price of 1x150W. So in the case my vote is for 1x150W HQI and add PC, VHO or T5 on the ends if you don't think the edges are well lit. Or you can run actinics in them too. Metal halides have high initial cost but you only have to buy 1 $60 bulb every year...


But this brings up a good point, with lighting being so important and costly in reefing, I usually choose my tank around my lighting budget. tanks are cheap compared to lights!

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