i have 3 apple snails living in a community tropical tank, just wondered if anyone knows if it is safe to put a piece of cuttle fish shell in to help them a little, as i have noticed their shells are not looking their best?

i have been informed i have hard water and lack of calcium for the snail is the problem?
they are fed very well by the way they eat most veg and prawn and blood worm.

thank you

wow that circular high tank hurts me eyes...and the poor little fish have no "breathing" room...fish need space to swim in. Never high and narrow...always long and wide.

As for calcium...I have had olive nerite snails for over a year, I have had trumpet snails and ramshorn snails for several months, I never need calcium supplements. Actually too much calcium is not good for shells.

I have rocks in my tank, when the snails graze over the rocks, the micro calcium can be absorbed into the snail...this is key to your problem, get some river rock. Do a test on the natural rock, if it fizzes after you apply vinegar the rock is no good.

The best rock is slate or sandstone. Boil the rock for at least 30 minutes. Cool it down in a sink with cold water. Then place it somewhere in the tank. The calcium in the rock will leech itself out over time, The snail will naturally absorb the calcium. Also when the snail graze for algae, microorganisms, etc, they absorb calcium.

I would stay away from any chemical. Let nature handle its own.

and by the way, cuttle bone can be placed in the tank, this is safe, but again, let nature handle it

hope this helps