I currently have 6 clams in my 110g but I have lost a couple in the last few years. No apparent reason although I am sure that it is just when I start to think "there ain't nothin' to keeping these darn clams"
Then phoof - it dies.
So the 6 I have in my tank are very very difficult to keep
I have just been using the Salifert all in one calcium additive but I really have to get one of my calcium reactor up and running as it is getting too expensive to use the Salifert.