too much light?

Well at night they should have their feeder tentacles out. What size tank do you have and whats the lighting?

how high off the water and how long of photo period?

It's very normal for SPS and LPS coral to open up to feed at night, because that is when, in a mature tank, tons of tiny bugs come out into the water column. During the day fish will nip at polyps which keeps them more retracted.
 
96 watts of LED's close to the water of a 20 gal tank? If that is true, then yes, that's a lot of light. That would be 32 - 43 LED's.  I'm wondering if you meant flourescent PC's or T5's ? That would be normal and not too much light.

What's the glass in between? Is it in the light fixture or a glass top on the tank?


Edited by Mark Peterson - March 20 2011 at 10:59pm

FYI, 24x3=72 but comparing LED wattage to MH or fluorescent is not possible.
I would raise the LED fixture a little higher and would definitely remove the glass top. Reef tanks should have the water open to the air. It is one way that the water can naturally stabilize at the proper pH of 8.0-8.3

Another thing to be concerned about: What are the Alk and Ca of the tank? 

i would raise it to 8" or so above the water

leds put out some crazy par on a shallow tank like that i bet your bleaching your coral having it so close. what size is it 20 Long, 20 tall, 20 standard

phys wrote: 20 standard. I havent seen anything die or bleach so far. There are some that are growing and everything seems to be doing well. I was just wondering about the behaviour. I've dialed down from 72 watts to probably 60 or a bit less. I'll keep everyone updated as to the progress of the corals i have in so far. I really cant put it any higher due to some shelving but if it becomes an issue, I'll put some diffusing material in or take some LED's out. Question, i thought bleaching was caused by high water temperatures and water chemistry, not so much lighting.

All three can cause bleaching. I would say that lighting is the number one cause of bleaching followed closely by the other two.

Usually increases in algae means you have an excess of dissolved nutrients in the water i.e. Nitrates. Cutting back on your feedings is probably the best course of action to fight the algae.

phys wrote: I only feed twice a day and its usually eaten by the fish in a few min. So i dont think i'm overfeeding... but i'll watch again to be sure. I've tested for nitrates and they're about at 5ppm. I'll be doing a water change tonight and we'll see where that goes.

Twice a day is pretty excessive to me. I feed my fish once every 3 or 4 days at most.

If your nitrates are at 5ppm that means there is plenty for the algae to eat.

I recommend not feeding your fish for 5 days straight and then feed them every other day after that. When you import nutrients the tank has to export them somehow or you start to have problems.

quite confusing. I hear feeding schedules all over the board.. so i'll see what works for me. thanks for the input though.