lighting question

[yzfr6]

I have vho's and metal halides (400). What time period should the MH's be on and how long should I keep the VHO's on? I currently have the vho's on at 11:00 am and go off at 10m the the mh come on at 4:00 and go off at 10:00 pm. I am having a little algae problem on the sand bed and was wondering if it was due to lights being on too long. Thanks for your help.

 

[pmrossetti]

Time period seems fine. I wouldn't go shorter with the MH. Maybe the cause is elsewhere rather than light. 400 seems alot for a 75g though. Algae or cyno? cleaner crew?

 

[pmrossetti]

Oops, quick add on. Sometimes old bulbs can do that. Have they been changed on time? thanks good luck