Bubbles bad for corals?

[RowSonic]

I never thought of this before. I have lots of brain corals, mushrooms and such and I never add water in my tank until the return pump produce bubbles because the sump's water is too low. Sometimes, I wake up in the morning and bubbles are all over the place in my tank. SOme of my hard brain corals actually have bubbles sticking on their slimes too but I never take them out. I just read about bubbles causing sudden death to corals. Is this true? Or is it just some types of corals are not good to have bubbles like sponge?

[jdieck]

Well, lots of corals are around heavy waving action with lot's of bubbles, the best indication is that if they slime avoid it because this is usually a defensive reaction.

[RowSonic]

K thank you. Can I ask you not using actinics in your tank really make the color of your corals fade or it depends on the type of corals?

[jdieck]

It all depends on the light combination you have. It is belived that on the contrary more light on the blue-UV spectrum (like actinics and 20 K) improves the coloration of the corals but I have found out that with many corals it is not the coral that changes coloration but how it looks to us.

On the oposite side wavelenghts in the yellow/Green and red spectrum may improve rate of growth.

I think that with excessive light a coral will tend to fade and get lighter instead of adding color and with too low of a light it will turn darker toward the brown side.

One thing about actinics is that it really helps to show the natural phosphorecence / fluorence?? (Do not know the right term) of the corals to make them brighter like neon bright.
In combination with Metal Halide in the range of 10K to 14K it will add growth and the shimmer lines for a real stunning effect.

[RowSonic]

Ok thanks. I actually recently upgraded mh bulbs to 175w 20k hamilton tech brand. I am not using actinic at all because the tank is blue enough. I hope this is good enough

[jdieck]

It will give you good coloration and moderate growth. Just insure that there is enough intensity (PAR) for the species you are keeping. 20K bulbs may have up to 30% less intensity than 10K bulbs
As a reference I keep sps corals and clams in my 225 and I use three 400 watts 10K suplemented by 200 watts of PC actinics.

For my 55 gal combination frags and Ref tank I use two 250 MH.

I started with 175 MH in my main tank (The 225) and once started with SPS they started turning brown which indicated that some of them were not receiving plenty of light.