light length 400 watt

[volivier]

I have three 400 watt metal halides, with two 72" actinic vho bulbs. How long would you recommend running the lights on a 135 gallon tank with acropora frags, zoa's, some mushrooms.

[110galreef]

How deep of a tank...maybe 4-6 hours should be plenty for the MH's and ~8 for the vho"s....400 is a lot of light with softies!

[Geoff]

do you have a DSB or a BB tank. i have found that with a DSB i could run my 400's all day 8 hours or so without any problems. when i went BB i found that i was having some bleaching occured, so i cut the lighting cycle down. i prefer to have the lights on all of the times, so i went down to 250w's this time.

G~

[volivier]

Originally Posted by Geoff

do you have a DSB or a BB tank. i have found that with a DSB i could run my 400's all day 8 hours or so without any problems. when i went BB i found that i was having some bleaching occured, so i cut the lighting cycle down. i prefer to have the lights on all of the times, so i went down to 250w's this time.

G~

I had DSB, but Vince thought my bottom sand was tired so I took out the top layer (that I could) of the new sand and sucked out the old and half the tank water too. Really cleaned it out good, took out a few rocks that seemed to emit algae, scrubbed the other rocks that had a little on it really well with a semi hard brush from Walmart. I did cut my lights by half, have since moved them back up to 6-7 hours a day again. After much reading I felt the light wasn't really the issue. More of a sandbed and feeding of dt phytoplankton. DT is gone....That dang DSB and BB is a killer decission.