MH to T5 questions

[Nhrafan26]

Current setup:
36"W X 36"D X 26"H tank.
Orbit Sunpod HQI 36" light fixture with 2-150W MH bulbs, 9 blue LED's and 9 white LED's.
Sunpod HQI | Current What's Next
I pulled the ballasts out of the fixture and mounted them separate to get more heat out of the fixture.
It is setting on the canopy right now which is about 10-11" above the water surface.
My problem is that you can clearly see a center column of light only in the center of the tank and the front and back are not getting as much light. I would like to do something about that but I really do not want to add any more MH bulbs to the mix as I don't want the expense.
I was thinking of switching to T5's so I could make a custom set up under the canopy with bright whites and actinics in the mix.
I am keeping mostly soft corals such as polyps, toadstool leather, mushrooms and a frogspawn. I also have a candy cane Saltwater Aquarium Corals for Marine Reef Aquariums: Candy Cane Coral
and a few others but those are the main ones.
I would possibly like to try a clam or something but it's not real essential in the plan. I don't think I can go with one now because the sand bed where I would put it is up front in the tank and out of the column of light, more in a shadow-area.
Is is possible to switch to T5's for about the same price to operate and maintain?
What are my options to light up a 36" X 36" tank area??

[charlie]

I am here but can I beg off and get back to you when I get some real internet??? I will be back home tomorrow nite, and will probably get back into the swing of things Saturday AM. Hope this is OK..Ce

[Ninong]

Is is possible to switch to T5's for about the same price to operate and maintain?

What are my options to light up a 36" X 36" tank area??

As you have already discovered, two 150w metal halides just won't work for a 36"x36" square tank that is 26" tall unless it is a tank viewable on all four sides and you are only interested in lighting a central pillar of rock.

The next limitation in using 150w halides on such a tank is that your options as far as Tridacna clams and most SPS are concerned are limited to placing them fairly high in the rock structure directly under each lamp. And that assumes that you are using good 10,000K lamps and not any of the lower PAR 14,000K or 20,000K ones.

I don't want to get into how much it would cost to switch from what you have now to something different because you can easily figure that out for yourself. To compare electrical consumption costs, just add up the total wattage. It really should be the wattage consumed by the ballasts but lamp wattage is close enough for government work. Then add up the cost of purchasing each lamp and how long you can expect it to last before replacement. Finally, add up how much it's going to cost to purchase new equipment and add that to what you have already invested in your current fixture, assuming you intend replacing it -- minus whatever you might get for it if you intend selling it. You can do that on your own.

Without knowing your exact set-up, I will assume that your tank is viewable on three sides and that you are interested in lighting the entire 36"x36" surface area as evenly as possible so that you can utilize the exposed sand bed for LPS and maybe a T. squamosa or T. derasa. If that's the case, then you could have accomplished that quite satisfactorily by going with HO T5 tubes in individual reflectors from front to back of your tank from the beginning.

I'm not going to get into all the possible ways to light your size tank with metal halides (and appropriate reflectors) because that would require a lot more expense and it would require moving up from 150w to 250w lamps (or even 400w lamps). Naturally, if you don't intend keeping SPS ever, then that doesn't apply to you.

You might want to consider keeping what you have and just adding HO T5s in front and back of the metal halide fixture? The truth is that your two 150w halides mounted 10-11" above the surface aren't giving you much intensity at all. Obviously you mounted them that high to get better spread over your 36"x36" tank. It's just that they can't cover that much area. Assuming they are typical 150w HQI DE lamps in typical HQI DE reflectors, their effective spread is no more than about 22"x20" and the intensity drops off dramatically at the edges. Since your lamps are in a 36" long fixture, you have overlapping coverage in the center of the tank but you have very weak coverage in the front 8" and back 8" of your tank (36-20=16/2=8). HQI DE lamps are only supposed to cover an area 20" in total (measured under the lamp, front to back).

Here's what you could consider: Lower your present fixture to about 7-8" off the surface. (I know that's probably not recommended by the fixture manufacturer.) If you're not already using the best quality 10,000K lamps, then switch. Add HO T5s in individual reflectors in front and in back of your halide fixture. Use as many as you can fit and that will work with your budget. Make sure that an actinic tube is just in front and just behind your halide fixture with the 10,000K lamps.

You probably don't want to consider switching from 150w to 250w halide lamps and that's probably not even possible with your present fixture (or maybe it is?). In any case, that would be expensive and totally unnecessary unless you wanted to go whole hog for intensity.

BTW, T. crocea and T. maxima should be place fairly high on the rock structure, not on the sand bed. I realize that many hobbyists do place them on the sand bed but that's wrong. Very wrong! These clams are both boring clams and they both require intense lighting, especially the crocea clams. They should be placed on the rock structure facing directly up. T. squamosa and T. derasa should be placed on the sand bed. The same goes for T. gigas, but that species would outgrow your tank after about 10 years, assuming you start out with a fairly small one. They grow fast and they get very large. You could still consider one but you would have to accept the fact that it would eventually have to be removed or it would take up the whole tank in 15 years.

P.S. -- Just to make sure we're talking the same language: When using a metal halide fixture, distance above the surface is the measurement from the bottom of the fixture (glass shield) to the water's surface. When using individual lamps of any kind without a ready-made fixture, distance is usually measured from the lamp itself to the water's surface.

[Ninong]

How to light a tank that is 30-36" front-to-back and 24" or more tall?

Examples:

High intensity lighting with just HO T5s

Tank dimensions: 64"L x 31"W x 24"H

Lighting: Ten 80w T5 bulbs in Powermodule Ati lamp

As you can see from the tank photos, Szymon Jankowski is an SPS specialist using nothing but HO T5 lamps.


Very high intensity lighting

Tank dimensions: 66"L x 36"W x 30"H

Lighting:
- Six Giesemann MEGACHROME Marine 400-watt single-ended 12.5KK MH bulbs
- Eight Giesemann T5 39-watt Actinic Plus bulbs
- Four URI VHO 140-watt Actinic Blue bulbs
- Six IceCap 400-watt metal halide ballasts
- Two IceCap 660 VHO ballasts
- Four Osram T5 Quicktronic eballasts

As you can see, Chingchai Uekrongtham likes SPS. A lot!

[Nhrafan26]

WOW, thank you for the response.
I was wondering about the depth because even some of the corals (polyps and such) that are at the bottom of the tank aren't really thriving. They just seem to be holding their own and I've been wondering if lighting could be the culprit.
I test (not as often as I should) and it's always lower than an ideal limit from what I've read. I change about 15-30G of water every other week or so and add trace when it's a little on the low side.
That's why I was thinking about the lighting.
I am not really too interested in keeping sps corals right now but I may try my hand once if possible.

Actually the light is at the height it is because of where it sits on the top of the canopy. I do have the legs for it but the fans at the ends will be blocked off and I'm not into cutting into it right now or I'd try lowering it.
I did set it on one day and you could REALLY see the column under the lights then.
I have a 4ft. PC fixture from my first tank that I was thinking of taking apart and mounting to the underside of the canopy just for more lighting. It has 2 actinic and 2 white with a couple LED's.
I would just have to get a couple reflectors to put behind the lamps and I could wire everything up.
I will have to check into what I could put together a T5 set up for as well.
Still putting something in the front of the canopy isn't ideal since that's where I feed from and also do a lot of tank maintenance at. Closing that opening up or making it less accessible wouldn't be ideal.
I will check into the parts and ballast(s) to see how much it will be to add a couple bulbs into the mix.

Thanks for the advice and the links.