What cause this?

[hillegom]

patpare: The caulerpa went asexual, you then have to take it out, otherwise, all the nutrients the caulerpa took out of the water to grow, will be redeposited back into the tank, spiking your nitrates etc.
This does not happen to cheato, All lot of people will not use caulerpa for just that reason.
Read this link, about middle of the page
http://saltaquarium.about.com/cs/alg...a/aa112000.htm