How many liters/gallons is your tank the snails will be going into? Some folk have had success with these 2 fresh water snails very very slowly acclimated to brackish water but these will breed like rabbits and take over you tank if not careful, some will argue that numbers stay low as they dont have enough food in the tank to reproduce but i've never been one to take the risk;
- Malaysian Trumpet Snails (MTS) - https://en.wikipedia.org/wiki/Malaysian_Trumpet_Snails
- Tarebia granifera - https://en.wikipedia.org/wiki/Tarebia_granifera
Then we come to Nerite snails, Nerite snails can be fresh water or brackish and do well in both, they will only reproduce in brackish water but its going to be pretty much impossible to get them to successfully have eggs that ever hatch, unless you are really looking to set up your tank to breed them purposely and you really know what you are doing. There are lots of Nerite snails:
- Zebra Nerite Snail - https://en.wikipedia.org/wiki/Neritina_natalensis
- Horned Zebra Nerite - https://en.wikipedia.org/wiki/File:Clit ... ema_01.JPG
Then we have another type of snail found in Hawaii that seems to do really well in brackish but i dont know anything about them as ive never kept them, @opae ula related
keeps them and has even had them reproduce in his tank so he would be better to ask.
- Pipipi Snail - Nerite picea
If you have a large tank and a lot of algae then why not go for a couple of zebra Nerites as they grow pretty big and bulldoze algae, if you have a smaller tank get a Horned zebra Nerite or 2 as they only grow a 3rd of the size of the Zebra Nerites and wont run out of food to eat in a small tank. When it comes to contaminates you are at the mercy of who ever sends them out to you unfortunately and most Nerites are kept in fresh water tanks when purchased so when you drop them in your tank they may not survive if they don't adapt. They are both fresh and brackish but when they travel in the post or get cold via travel it can reduce their chances of transitioning over for one to the other.
For substrates take a look at this part of my guide: http://opaeula.co.uk/page/how-to-setup- ... #subs_decs