200G Lighting suggestion

[nickjj]

I currently have a 200G acrylic tank that is 60"long x 30" wide x 25" deep and want to replace my two 250w MH fixtures and T5 actinics. I'm moving more toward a fully stocked sps tank and need to bump up my lighting. The tank only has two openings in the top and it would make it difficult to add anymore metal halides.

I would like to know what the best configuration for the 24" PR-156W would be. Could I use only two and will the coverage be enough for the full 60". Or would three be necessary.

Also how high should they be placed above the tank since it is acrylic and want to avoid heating the top of the tank.

[JayinToronto]

Nick,
I own 5 PR-156 with the 90 degree lens. My tank is 6' long. They sit 7 inches above the tank. I find that the light is very focused and it's not until about half way down the tank (the tank is 4' tall) that there is good coverage. I know that the PAR (PUR?) for these lights falls off very quickly once you are even an inch out of the focus zone. I've tried to look on line for specifics of the angle of the light beams to try to make some decisions about coral placement but haven't been able to find this specific info. My recommendation to you is to find out the EXACT light footprint at varying distances from the light before making your decision. If I can find someone to lend me a PAR meter I may be able to map this out better for everyone.

[nickjj]

Thanks Jay for the input, I don't have a very deep tank and was understanding that the PR-156W with the 120 degree honeycomb cell would be better suited for my tank being only 25" deep.

I will most likely start with 2 since basically I have 2 rock islands on either side of the tank after a discussion with the Canadian distributer today.

I will start by mounting them end to end closer to the front of the tank across the width at a bit of an angle pointed at the rock. I'll see how the light coverage will be like first otherwise I'll probably purchase a third and mount them perpindicular to the width of the tank like yours.

[mr.wilson]

Hey Nick,

I can lend you my Apogee quantum (PAR) meter so you can get real life numbers for your tank. Conditions are so variable, its impossible to go by PAR tests conducted out of water with no rock work influencing the numbers.

Orphek has the most PAR per watt and the highest PAR over a 24" x 24" area, making it the most efficient LED on the market.

I some cases, the PR 156 works best neither parallel nor perpendicular to the tank, at an angle. It really depends on your rock work. Your two island rock formation may be such a case.

Shawn
Orphek Canada

[nickjj]

Thanks Shawn I will definately take you up on that offer. It would be good to get some idea of where my lights are today considering the tank has been running the last three+ years with this light setup.

I figured starting with the two fixtures would probably be similiar to the two MH lights running currently. I can always add a third. Any concern with the fixture over the acrylic center brace?