How are you getting low nutrients? Or I should say, what are the levels of nutrients? they can play a really key role in the vibrancy and health of your corals, although SPS are generally more affected by low nutrient, high alk tanks. Chef is right though, running high alk in low nutrient tanks, or even ULNS, can cause the coral to try and grow more quickly than it has the ability. LPS are generally OK though. I have an ULNS system that needs NO3 dosing to get it up to acceptable levels (2-5) but have had some periods of high alk, high CA and high MG without any adverse affect on Acans and Favias. Actually they grew and had babies during that time, but when alk comes down, color returns, same with NO3, when I bring it up, color and growth really come back... Something to think about. If you have ultra low NO3, take a look at nitrate dosing, esp with the RSCP since it's always going to give you high alk
