lighting question for ninong

[corey0613]

hi,

sorry to call you out but your responses are always so educated.

i am wanting to upgrade lighting on my 25gal in the wall tank. i know that the tank is small but that is not going to change.

the 2 fixtures that i have in mind are:

1. 175W MH with a single 4" cooling fan

2. 250W MH with 2x28W pc actinics with dual 4" cooling fans

i do not have the budget for a chiller (and never will) so please keep that in mind.

my goal is to be able to keep SPS and clams

the 250 is a better buy but i am concerned about heat issues.
i plan on having the fixture about 6-8" above the tank.

any ideas, suggestions, or feedback would be greatly appreciated!!!!!

[Ninong]

I would not go with any of the choices you have listed for a 25-gal tank where heat is an issue. I suggest you consider a single 150w Iwasaki 50,000K medium base lamp (I'll have to look up the model name and don't let the 50,000K fool you, that's just a marketing gimmick) or a single 150w 10,000K HQI DE lamp. If you are able to work in a small actinic fluorescent lamp for dawn/dusk effects and supplemental actinic light that would be a bonus.

I am afraid that a 250w metal halide would be out of the question over a 25-gal tank if you are concerned about heat and a 175w mogul base MH lamp is not as good as a 150w HQI DE metal halide lamp.

[Ninong]

Here is a comparison of the Iwasaki 150w 6500K vs. the Iwasaki 150w 50,000K: http://www.coralreefecosystems.com/l...put%20Analysis:

The color of the 50,000K is very pleasing all by itself by the 6500K does put out almost twice as much total PAR. However, either one would be a good choice for a 25-gal tank. The 6500K just wouldn't look as nice by itself, it would need actinic supplementation.

Another option would be to go with PC fluorescent lamps, assuming your tank is at least 24" long.

Giesemann makes a very nice 150w HQI DE fixture called the Nova-II. You could consider one of those but they are pricey. Aqua-Medic (AB Aqualine) has a new 150w HQI DE Plus fixture that has a single 150w HQI DE lamp plus two T5 actinics. I believe it is 24" long. (P.S. -- It's called ocean light 150+ http://www.aqua-medic.de/index0.html It comes with a single 150w AB 10,000K HQI DE lamp (actual color temp = 13,000K according to AB) plus two 24w T5 actinics. That would be a really first class solution if you want spend that much.)

Picture of ocean light 150+
http://www.aqua-medic.de/cgi-bin/php...id=166&field=0

[corey0613]

if i went with PC's would i be able to have SPS and clams? i currently run 2x65W and that isnt close to enough "light". i have seen a retro @ hellolights that i maybe intersted in. it is a 4x55w setup, for a total of 220W of PC lighting. and my tank dimensions are 24x12x20.5. the height of the tank is why i wanted the more wattage in the halides, that way i would be able to keep clams on the substrate. let me know what you think about the PC's!


thanks

corey

[Ninong]

Corey,

When it comes to light, the only thing that matters is the amount of light incident on the animal in question. That means that animals in the top 1/3 of your tank will be receiving about three times as much light as animals on the sandbed given the restrictions implied by the size of your tank -- it's just isn't practical for you to consider something like 250w metal halides without running into serious heat issues.

There are other limitations on your selection of animals due to the limited water volume and dimensional restrictions of your tank. Even if you had sufficient light, you do not have sufficient water volume for any Tridacna spp. clams other than possibly T. crocea. You could keep a T. maxima for a certain period of time if you started out with a small one but at some point it would be too large for a 25-gal tank. It would be a serious mistake to put a small T. derasa in a 25-gal tank because it gets very large very fast.

Of those three species, only the T. derasa is found on the sand in nature. And, unfortunately, the smallest one -- T. crocea -- requires the most light because it is found naturally in shallow water imbedded in hard substrate or coral. If you want to keep one, maybe two, T. crocea clams in your tank, you could definitely do so with a 150w 10,000K HQI DE lamp provided you positioned the clam(s) in the area of your tank beneath the metal halide lamp and high up in the rock structure, not on the sand bed. You could keep a small T. maxima that way, too, provided you understand that eventually you will have to move it to a larger tank.

SPS is pretty much the same story. As long as you can get enough light to the coral polyps you can keep whatever you want. That means that your SPS should be positioned in the top half of your tank and closer to the center of your tank. Use the lower half of the tank and the sides for LPS or softies.

[apophis924]

Corey i would go with the 250 MH. as far as heat issues goes the heat issue with MH is a bit over stated. I run a 250 MH over a 20 gal tank. my fixture is less than 3 inches off the water . I have one small fan mounted on the side of the tank that blows air across the top of the tank. my temps hover around 78 to 80 degress. The tank is open top and not enclosed in a wall. that might be a problem with your set up. Open space is the key to running MH over small tanks. If you keep your abient room temp between 70 and 75 and have good air movement the heat issue will not be a problem, and if you mount your fixture 6 inches or more above the tank you should be good to go.

[corey0613]

what you are saying about the heat issues seems to be the overall concensus on other forums that i have posted on (3). with advice coming form persons who actually run this type of wattage on "small" tanks. no one has had heat issues. the fixture has 2x4" fans in it and i plan to have another 6" fan blowing on the surface. thanks for the advice

[apophis924]

Glad to help out. with that 250 MH set up and the two actinic that is an awesomne set up. I would use a 10k bulb But with the actinics you can go as low as 6.5k bulb which gives better coral growth but not as pleasing to the eye if not supllmented with actinics. at anyrate the set up you are working on will no longer make lighting a factor in determining what types of corlas /clams you can keep. You will find it very difficult to make a choice since now you can keep any high to med light animals you choose. Just be sure to acclimate your low light animals to the new lighting. I didnt do this and lost a few shrooms and an brain coral. But otherwise the animals adapt very well. If you still have problems with evaopration you can shorten yoour photo period. Mine used to be 12 hours now it is at 8 hours. saves $$ and since my lighting is so intense it is more than enough for my animls.
Enjoy.