250 vs 400

rayn · Mar 23, 2016

I am running dimmable Mh ballasts.

Which is better for coral, 250 or 400. Or is it per tank depth?

hybridazn · Mar 23, 2016

It depends on tank depth really. Anything deeper than a 24" tank I would probably run 400w. That is of course if you want to be able to grow sps on the sandbed haha

clownfish chris · Mar 23, 2016

hybridazn said:
It depends on tank depth really. Anything deeper than a 24" tank I would probably run 400w. That is of course if you want to be able to grow sps on the sandbed haha

I have to agree. My tank is 24" and I am doing fine with the 250. I need to borrow a par meter to see where I am at though.

rayn · Mar 23, 2016

My 120 is right at the 24-25" mark depending on what or where you measure.

Just didn't know if I was good with 250 or not. Not planning a heavy SPS tank, but also don't want to fry corals under 400.

clownfish chris · Mar 23, 2016

I would definitely go with the 250 then. If it was SPS heavy or deeper, 400 would be okay.

ECreefer · Mar 23, 2016

Can also depend on the fixture and height of that relative to the water. Personally I wouldn't run a 400w unless I had to. I can get about 200-500 Par with a LumenBright Large at 15" running a 250w Radium

143MPCo · Mar 23, 2016

How do I select the proper wattage metal halide bulb in relation to aquarium depth?The depth of an aquarium affects light penetration and light intensity.

175 Watt - Recommended for aquariums up to 20' deep or mixed corals with a few SPS and clams placed high in aquarium.

250 Watt - Recommended for aquariums up to 30' deep with mixed corals including SPS and clams.

400 Watt - Recommended for aquariums up to 48' deep or a dedicated SPS and clam aquarium.

ECreefer · Mar 23, 2016

What kind of fixture are you thinking of running?

rayn · Mar 23, 2016

I have a Hamilton fixture, but running ?illumitek? ballasts. They are 250/250ho or 400/400ho.

ECreefer · Mar 23, 2016

Depending which Hamilton fixture it is, the 250 might not provide the punch needed for a 24" tank. The Cayman and cabo, I think are the names, are more of a spread fixture, good for large areas but not a lot of PAR past 12" or so. The other more condensed fixtures, not sure of the names, might have more PAR deeper down. Just don't have any experience with tbem