Mh 250 Vs 400

[hstac]

i have got to upgrade my lights. my current aquarium is a standard 120gal reef. lots of softies and 1 candy. everything is doing very well but i'm fighting with algae, esp a diatom bloom that just won't quit. phosphates are zero and i have chaeto in my refugium. standard cleaner crew stays busy. my sand is good quality, not for a playground. my water tests fine both with my home tests and at the lfs. my question is this... why would i choose 400w MH over 250w? i've selected my pendants, ballasts and bulbs but haven't decided on the wattage. ideally, i want lights that will support anything i decide to put in the tank. i have my eye on a couple of clams and i really like the LPS corals. so... 250 or 400? what's the general consensus????

[reidcrandall]

I have a 120 that I'm working on setting up right now, and I had the same conversation not too long ago... and even had a second thought or two after I bought my 250s. I think the consensus is that you should be fine ith 250s on a 120 and be able to keep pretty much anything. Your issues with algae may have more to do with the color temperature than the wattage.

Also, more than one person has had phosphates test out at 0 during an algae outbreak. That's most likely because the algae is using up all of the phosphates that are being added to the tank or are being leached from rock or sand.

What kind of filtration equipment are you using?

[mg426]

Couple of comments here. 250 watt lighting will support anything you put in the tank. If you have algae you have Phosphates.