[jiggly75]

Hello,

We just upgraded from 2 175 watt MH's to 2 250 Mh's. We ran the 175's from 10 am to 9pm. Should we cut back 2-4 hours until the corals get used to the lighting change?

[Reefland]

I don't know if the change from 175's to 250's will require any adaption; you should monitor closely and adjust if necessary. If you were going from VHO/PC/etc. I would say definitely.

[Ninong]

Originally Posted by jiggly75

Hello,

We just upgraded from 2 175 watt MH's to 2 250 Mh's. We ran the 175's from 10 am to 9pm. Should we cut back 2-4 hours until the corals get used to the lighting change?

Your goal is to try to avoid abrupt changes whenever possible. Whenever you increase the intensity of your lighting, either by replacing old lamps with new ones or by changing the size of the lamps, it's always a good idea to make appropriate adjustments to mitigate the sudden increase in intensity.

In an ideal world, you would do this by raising the height of the lighting fixture above the surface of water until the intensity of light incident on the corals matched the previous intensity but this is not always possible. When that is not practical, you should reduce the total photoperiod.

About two weeks ago I replaced the 250w 10,000K HQI DE lamps in my fixture with new lamps. I reduced the photoperiod by 2 hrs/day and I am increasing it by 1/2 hr/week until it is back to its previous setting. It would have been better for me to simply raise the light fixture but unfortunately I can't find the stupid steel suspension cables, so my fixture is sort of stationary right now.

If I were you, I would reduce the photoperiod by about 3 hrs/day and then gradually increase it back to your previous photoperiod over a period of three to four weeks. It takes a minimum of three weeks for corals in the wild to adapt to permanent changes in light intensity.

[jiggly75]

I think cutting back 3-4 hours would be a good idea. Better safe than sorry! Instead of running the MH's from 9 am to 10 pm. we will run them from10:30 am to 6:30 pm. Increase about an hour a week until back to normal.

Thanks for the info.

[charlie]

They allso have plastic screening that you could put over your tank in layers. Take a layer of screen off a week and it will probably have the same effect!!