What spectrum bleaches coral

[hyde7278]

was checking to see if it's the blue spectrum or white spectrum that bleaches coral.

I was away of a week and had a friend take care of the tank and he mistakenly changed my light from custom to sunny setting which caused a alge bloom and bleached a coral or two.

So I wanted to know if I use just the blue spectrum for a few days to calm the alge should I turn the intensity down or keep it the same.

 

[mcarroll]

It's the intensity shift more than a color change.

 

[hyde7278]

Ok I'll turn down the intensity a little and give the coral a break to recoup

 

[mcarroll]

They tolerate small lighting increases since damage to them is minimal and they can usually tolerate it fine, repair themselves, and "move on".

In nutrient-starvation situations where nitrates (and maybe phosphates too) have been ultra-limited, corals may have a harder time repairing themselves, so the stress to them from lighting changes is greater.

This effect is hard to predict sometimes too because corals (and their microbes) are very conservative with nutrients – it is possible that they can have plenty of N and P on reserve while the water around them has almost none. (A consistent heterotrophic feeding source is usually involved.)

Corals don't necessarily require a large surplus of nutrients in the water, but they do benefit from a very consistent supply of nutrients – whatever the source or concentration.

 

[mcarroll]

If you click on my blog, there's a tag cloud on the left where you can click on "Light". I have lots of good journal articles linked on this subject.

 

[hyde7278]

Thank you for the info. My nutrients have run high from when I got the tank and I have to do tests in he morning but I wouldn't be surprised there running higher then normal since I pulled my filter floss before I went away since I worried that the person taking care of the tank would forget to change it. So after testing I'm going to do a 50 % water change.

I'm sure the nutrient level has something to do wi the alge breakout. And it doesn't hurt that the lights were on 24hr at a higher intensity.

I'm just glad that it didn't do more damage.

So my plan is to do a water change and turn down the intensity on both channels and work my way back up to my current lighting schedule.