400 watt XM

[adamRS80]

I just had a quick question for some of you guys. After seeing my tank a friend of mine wants to switch from a full VHO setup to one or 2 metal halide, probably using XM bulbs. My question is would one 400 watt MH bulb mounted in the center of the hood perpendicular to the front of the tank, with a good quality reflector be able to reach the majoriy of the tank. Keep im mind he will still be using 2 or 3 140watt VHO's running the length of the tank. It's a 125 gallon and is a little over 60 inches long.

[Texreefer]

it will be perfect for the two foot center of the tank where he puts it.. but the ends of the tank will recieve no benefit and it might look strange with a really bright spit right in the center

[witecap4u]

Im running two 400's on my 100g with two 4ft vho's and it looks fine. Tank is 5ft.....

[Jimnorris]

I run 6 perpendicular on my 8 foot tank not counting the space for my center brace. At best I am getting about 12 inch coverage from each lamp. IMO I would use 2.
Jim

[matt]

If your tank is 60" by 18", I'd consider running 2 parallel with the tank length. Use the PFO parallel reflectors, not the perpendicular ones. Sanjay Joshi did a study on these reflectors; if you're using 2 over this size tank, you need to light an area 18" by 30" with each bulb. The parallel reflectors have a light spread that's closer to this (rectangular) than the perpendicular ones (closer to a square) If you use more bulbs, like 3 over this tank, each bulb needs to light a 20" by 18" area; for that the perpendicular reflectors would be better.

[adamRS80]

Thanks for all the help. it sound like using two is the best way for him.