Possibly baby horned nerite snails?

[Shaihulud]

I have come across a species of pond snails that have an operculum or trapdoor, this looks exactly like those. They stay quite small though and doesn't multiply very quickly.

[jeffteo]

Last night I did a test by putting a supposingly male together with the other 2 sex unidentified Nerte snail and within a short while it start climbing on top of the 2 sex unidentified snail one after another after I removed one of it.
Does anyone knows if the one ontop is confirmed the male? Seems like i have 3 female and 1 male in tank and that explains why the eggs laying is never ending.

By the way, anyone can advise how to I make a full marine tank? Just add marine salt to tank water till it reaches 1.02 on the gravity meter?