Thanks for the comments everyone.

The rock work only falls if I am clumsy while working in the tank...and usually it is the smaller pieces. Otherwise, for the most part it is very stable ...nothing within the tank has ever induced an avalanche (knock on wood).

I too am very excited to see the sps fill in. I am already noticing an increased demand for ca and alk. I am glad I've got that reactor on the way.

R, Jamie