My leather coral has recently (with the last 24 hours or so) begun to bleach out. I did some internet research but the only thing I found was a reference to the coral expelling some of it's internal algae and looking lighter. I guess their color actually comes from the dinoflagellates that live in the soft tissues? They can expel too much when stressed? The two things I found were: the pH is high at 8.8 and the salinity is high at 1.025 due to evaporation. There is zero ammonia and nitrites. The chemicals are within normal parameters for this tank. Last water change was about 30% done 09/07/10.
1. Type & how long you have had it: leather coral, at least 1.5 years.
2. Current lighting & Bulb Age: Coralife Lunar Aqualight 72" with 2 96-watt 10,000K Daylight and 2 96-watt blue actinic bulbs. Replaced 03/01/10.
3. Nitrate: 20
7. pH: 8.8 (normally at 8.2).
8. Salinity: 1.025 (normally at 1.024).
9. Temperature: 82 (normal for this time of year).
10. Liquid or strip test kits: I used both, same results.
11. Location in tank: Not in direct sun, has not been moved in 1.5 years.
12. Current amount of flow: total of 3,914 GPH. I have two SEIO Prop pumps in the tank (flow rate 1000 GPH), two RIO Aqua pumps in the sump (flow rate 782 GPH) and one Mag Drive 3 pump on a Remora Pro skimmer (350 GPH).
13. Current tank dosing regimen: I do not currently dose the tank.
14. Nearby coral: a very small anchor coral, long-tentacled anemone and some macroalgae.
15. Explanation of problem: The leather coral was pretty much the same color as the anemone up until when I noticed it today. It looks much lighter, but still has it's polyps out to feed. I did add fresh RO/DI water today and will check the salinity again tomorrow.