lighting ?

Hi ... we bought metal halides for our 75 gallon reef tank. The tank seems to be rejecting the light. The fish don't really care, some stay mostly under the rocks, others come out, but our corals don't look good. This is after the adjustment period... this has been going on for awhile. We have a leather coral that was at least four inches tall when we got him, now he only stands up about an inch, maybe. Xenia don't really seem to care, but our goniopora liked the power compact much better. Our stony corals keep dying, and where we once had coralline algae growing on the rocks, we have no more. It disappeared. It is still on the rocks where the "sun doesn't shine" so we are 99.9% sure it is the light. Water is good. Everything is wonderful- except the light. We are actually so frustrated with it that we are considering trading it (and the stony corals) in for a power compact or T5 or something lesser.

Anyone have any experience with something like this? What do you suggest?

 

How many halides and how strong (wattage)? i don't use halides on my 55 gallon, i have PCs and im happy. Has the leather coral changed color or look Any different? I know some corals are getting enough light when they are close to the rock there on. but really it would help to know the intensity first

 

by the way.......hope your corals make it, its always sad to watch your little critters go before your eyes....

 

Are we talking about 400W over a 10g ?
What size tank, and what type of ballast, and bulb temp (kelvin rating)?

 

that would be quite intense, like a deep fryer for corals and fish. i could see them brown and crispy, tantalizing my taste buds...... dangit not again, sometimes i see my self as a person who shouldn't keep fish for a hobby:

 

ive got 96 watts of t5ho over my 35gallon, it colours the corals great .
I also tried to put a 400w m/h on the same tank
you would get what i would get and thats a Coral and fish soup!!

 

You don't need less light, you just need a bigger tank.

 

Hey Stefanie, my first Question for you is, what was your lighting system before you bought the MH'S. If you went from pc's to mh's over night(so to speak) that could have a impact on some corals. Have you checked ALL water chemistry?? I also have a 75 and MH"s and my lighting wattage is 692. what wattage and (K) bulb are you using?

 

It is very Important that your corals are acclimated to your new light. There are several ways to do this but the easiest way is to cut you photo period way down when you upgrade and slowly over several weeks increase the interval until your back to normal. It is possible that some of your Soft corals with tank weeks to months to get used to your new lights.

J

 

Sorry... the tank is 75 gallons... there are two 150 watt MH lights with actinics and lunar lights that help the photoperiod be more "natural." The MH and actinics turn on at about 7:30am and go off about 9:30pm, and the lunar lights stay on in between. There was no other light before this one... we bought the MH when we bought the 75 gallon. The store we buy from use metal halides over most of their tanks, including coral tanks, so we figured it would be okay. We have a 30 gallon tank in the same room and those lights come on about 15 minutes before and go off about 15 minutes after our 75 gallon tank.

The stony corals are really the ones that aren't great. The leather really opens up a lot at night, and sometimes during the day, and our frogspawn and xenias really look pretty good. Not ideal, but pretty good. I just think it is strange... aren't the stony corals supposed to "thrive" under metal halide?