Why do anemones care about calcium levels at all if theyre softys?

[EnderTurtle]

Anemones are not stony corals or corals at all.

Why do they care about calcium levels? So long as youre at at least 400ppm

 

[GroktheCube]

I'd assume that they rely largely or entirely on calcium dissolved in water for use as an electrolyte. Major imbalances between levels of calcium, sodium, and potassium could cause problems.

Total shot in the dark/guess, but it's the best reason I can think of.