Is It Possible To Overlight Your Aqaurium?

[jeasko]

Ok finally got my mh unit up and running using a 250w 10000k Mh lamp, just wondering if its possible that i may have over done it and a step back to a 150w would be a better idea?

 

[Colin_T]

how big is the tank?

a 250w metal halide is fine on most tanks but there are a couple of things to consider. Make sure the light is high enough above the tank so it doesn't heat the water.
If you have corals or plants in the tank and they aren't use to the brighter light then only have the new lights on for a few hours per day. Then increase the photoperiod by an hour each week.
If you put too much light on corals and they aren't use to it, they can bleach.

 

[jeasko]

tank is 39x 18 x18 inches, was more worried about over lighting the corals, so guess i should reduce the lighting times by a few hours as have kept it the same as when i was using t5 for the past week, was more worried that it would damage the corals by suddenly improoving the lighting that mush so soon.
guess its time to re adjust the timers!

 

[SkiFletch]

Ah, you're worried about burning the ones towards the center of the tank? A valid concern. Try starting with a 4 hour light cycle and slowly building it up to 8-10 hours over the course of a month or so.