my reef GARden frenzY: BLEACHING

this was a beautiful green sps which showed a darker underside

I had been fretting over the bleaching of my sps since some time ago when I still had tank 2 with my AquaBeauty 70W LED lights. What I knew was bleaching of corals often happened under 2 scenarios which cause the zooxanthellae to be expelled from the cells (photosynthetic algae living in the tissues of corals) - 1) high water temperatures or 2) intense lighting.

I couldn't understand why my sps often ended up being bleached with poor polyp extension (pe) and suspected undesirable or unstable water parameters as the cause. I also blamed insufficient dosing of amino acids etc and my LED lights for being not powerful enough to keep sps. But when I started my new tank 3 with newly mixed sea water and a brand new set of Maxspect Razor 120W LED lights which is one of the most popular and best lights used by the local reefing community, and my newly introduced sps continued to bleach, I was completely perplexed. Then when I was fiddling with the lighting intensity today and switched all the lights off, I started seeing something which never occurred to me in the past.

I noticed that the few bleached sps were not totally or completely bleached from the bases to the tips. If high water temperature is the cause, then I figure it would make sense for the entire sps to be bleached. However, what I saw were that the portions of the sps facing the lights were bleached while the bases and areas not facing the lights were darker or lightly coloured. This could only mean that it was the lighting that caused the bleaching. Very often, I thought that only the white lights could cause bleaching and I had been so disturbed with the bleaching that I always overcompensated for it by turning up the blue lights (PAR 400-700 nm) to the maximum for almost 24 hours daily. This meant I was irradiating so much photosynthetic active radiation on the sps that their zooxanthellae were photosynthesizing 247 and eventually it became so saturated that they were expelled from the coral tissues.

Oh my gosh, if I am correct, I actually killed so many beautiful sps because of my pure stupidity and ignorance. With this revelation and realization, everything seemed to make sense and fell into place now. No wonder the pocci in tank 2 right at the bottom of my tank showed better colouration compared to the purple stag, the pink birdnest, the pink and the blue Millepora which were nearer the top and bleached first. I immediately removed the AquaBeauty which I just added 2 days ago to supplement the blue lights of my Maxspect and adjusted the intensities of both the white and blue lights to below 50% and duration of the lights to a maximum of 14 hours to give the corals some darkness for almost 10 hours.

I crossed my fingers and hope my suspicion is right and that the measures I have taken now will help the bleached sps to recover soon. By the end of the month, I am sure I would have some findings to post.