Hey Pauli,
How is the water quality/chemistry of your tank? When was the last time you checked nitrate, pH, alkalinity, calcium and magnesium? All of these are important to have balanced in your tank. Here are some links about reef chemistry and chemistry calculators :
Aquarium System Volume Calculator:
http://home.comcast.net/~jdieck1/volcalc.html
The Reef Chemistry Calculator:
http://home.comcast.net/~jdieck1/chem_calc3.html
What is Alkalinity?
http://advancedaquarist.com/issues/f.../chemistry.htm
Calcium:
http://advancedaquarist.com/issues/mar2002/chem.htm
Magnesium in Reef Aquaria:
http://www.advancedaquarist.com/issues/oct2003/chem.htm
How to Select a Calcium and Alkalinity Supplementation Scheme:
http://www.advancedaquarist.com/issues/feb2003/chem.htm
Solving Calcium and Alkalinity Problems:
http://www.advancedaquarist.com/issues/nov2002/chem.htm
High pH: Causes and Cures:
http://reefkeeping.com/issues/2005-03/rhf/index.htm
Low pH: Causes and Cures:
http://www.reefkeeping.com/issues/2004-09/rhf/index.htm