150w or 250w de MH for 19" water depth for sps?

[Pomme]

150w or 250w de MH for 19" water depth for sps?

Just wondering on what you guys would go for. As i could get some 150w downlighters, which i think would look smart. Or get some 250 watt units.

Also whichever one you think would be best, how many would you go for in a 7 x 2.5 wide x 19" water depth.

Thanx

Andrew

[Ninong]

You could go with either but the 250w size would probably be my choice, assuming you can handle the heat issues.

I would recommend at least four DE lamps for a 7' long tank but you could get by with three or you might want to consider five. One problem you will run into is that DE lamps with their particular reflectors will not fully cover your 30" front-to-back dimension. Some of the reflectors for mogul based lamps would be better able to cover that space if they are mounted parallel to the front glass instead of the usual perpendicular.

Absolute minimum would call for three lamps, either 150w or 250w DE type, mounted 12"-14" above the water's surface. You would get better coverage with five lamps mounted in a "W" pattern -- two of them set back about 12" closer to the rear wall of the tank than the other three. You might even consider going with a combination of 10,000K and 20,000K lamps if you like that appearance. This pattern works well for the typical tank with two rear corner overflows.

Another alternative would be three, four or five 250w mogul based metal halide lamps mounted about 10"-12" above the water's surface and parallel to the front glass. Three would be the minimum, four would be adequate but five would allow you to mix two 20,000K lamps between three 10,000K lamps.

You didn't mention anything about actinic fluorescent supplementation, so those suggestions are based on metal halides only. A more impressive display could be had by adding some actinic supplementation to your metal halides.

[Pomme]

Thanx for the reply mate,

I dont think heat will be a problem, as will see whats its like fans, and also extractor fan, but am thinking of a chiller also.

I know the reflectors for the 250s are good as i already have 2 250s. And it seemed to do 30" just. But i am not sure about the weir arrangement yet. As i might go for the wier to stretch the full back length of the tank for room for 2 dursos, 2 returns, 3 closed loops (inlets and outlets) and have 4 tunze streams hidden in it to. Or i might go for two weirs that have sloping sides so the tunzes go at angles towards each other, but have the bottom of the weirs connected so they are the same height but thats a thinking point.

I am thinking of having it all in a box frame which comes down from the ceiling, but will be on a moveable rail, so can be moved when i want to play around. But will also have it so i can alter the height. So will have the leights around 10-15" from the surface.

Just had a thought and i may go for 4 250s (as the tank has three cross beams) so has four compartments. and then go for 6 150s as supplements instead of actinincs.Or i could go for 4 250s and then the deltec t5s as actinics?

[kevinpo]

I would use the 250's. I'm using 400W mogul bulbs over 16" depth and they are a little too much light for most corals.

JMO.
Kevin

[Pomme]

cool thanx kevin, ill go for the 250s, what do you think about the idea of using 150w halides rather then the actinics. The price will be the same. And i was thinking of using 20k and 14k bulbs so would have the same effect, would it?

[kevinpo]

20,000K's are pretty close but not quite the effect of actinic bulbs. Actinic bulbs really give that twilight effect IMO,

Cheers,
Kevin