starburst polyps

Question
My starburst polyps have always been great, they grow well and look wonderful. But i have noticed that the last few days they have not been opening up. I am really worried and would love to fix the problem. I have had the tank for quite a long time with the polyps in it and never had a problem. Could you please give me a few ideas on what could be causing this? thanks!

Answer
Hi Robyn. First of all have you tested your water for ammonia, nitrites and nitrates? Is your pH, Temp. and salinity where it should be? Secondly have you introduced or used any new products into or onto your tank? These polyps will often close up due to a change in any of these things(water quality, new lighting, a change in salt brand additives new food etc...) and will usually either get used to the change or stay hidden until corrected. The use of iodine in your tank will lead to the lack of expansion and eventual death. They are also sensitive to phosphate absorbing sponges and these should not be used in their presence. Sometimes when whole colonies of a certain species fails to open up it could also be due to a predator in your tank.  There are lots of little things that prey upon these polyps so look closely to see if anything unusual is in there. I hope I gave you at least a place to start!