Snail And Fish - Water Very Soft I Put Charcoal Dirrectly In The Grave

[lucc]

Hi another question. I have a new snail. But my water - it is desalinated water - there is no other saurce of water on this island. So I am worrie that my new snail will have a problem with forming the shell. So I put some new charcoal which is for the filter and put it directly in the gravel - for the time being only little bit. Is my fish going to be ok, can I slowly carry on and adding some more? U see the hardness here is 0 - nothing. My botias macr. are picking it up as they digg in the gravel is it safe for them? Or is there any better way how to make the water harder? It it is safe - I think this is good way, will it last for ever or do I have to keep adding in in the future. My concern is - if it is safe... I saw the fish shop have it in some of their tanks. When I asked the staff working there about the snails and very soft water - they didn't have any idea and think that I worry too much. You see - they don't even know why their boss have the charcoal there in the snail aquarium? My question is - is it safe for fish, for botias m. picking it up in their mouths etc... I have it in the aquarium now for 5 hour - and everything seems ok... thanks Lucc