What snail is this?

The add said "black pond snails"

I'm guessing a Trap door snail

Viviparis malleatus possibly?
 
It's a Trapdoor snail. Plant-safe, and you could get it cheaper than that.
 
Q: Will these snails work in an unfiltered pond with no filter/pump system?
A: YES! These will definitely make a difference in an unfiltered pond. They will do the job of a filter NATURALLY!


That made me giggle
 
Will they take care of various algae and survive in an 6.8 pH tank? Or have any suggestions for a snail that will? My zebra loaches keep eating all the small pond snails.
 
Will they take care of various algae and survive in an 6.8 pH tank? Or have any suggestions for a snail that will? My zebra loaches keep eating all the small pond snails.
While the vivs do eat algae, that doesn't mean they make efficient algae eaters. They never seem to be that way in my experience and prefer cooler waters of at least 74 degrees. Your pH is very low for any snails. No snails can ever keep their shells in perfect conditions at that acidic state of water nor will your zebra loaches spare any snails in the same tank where they are.
 
a good filter and a UV sterilizer would take care of your pond issues.
 
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