well..not that i really recommend it because they wont do well...but margarita snails.
I too had cyano and my lfs had these snails that were listed as "black turbos"....they claimed that they would eat cyano. They were cheap so i figured (what the heck..i'll lose 2 bucks if they dont work) so i got a few and to my surprise they did eat it a bit. So i got more...like 15 total, and together they ate lots of the cyano, along with much of the other algae...great little snails, HOWEVER......
They're not a tropical species...they're temperate, meaning a colder water species. They often do not do well in aquariums because of the temp issue, tho they are in warmer waters for about 3 months of the year...and thats about how long it took for mine to croke

I then found out that there's no such thing as "black turbos" and that they were actually margarita snails. grrrr! lfs rip off again!
so, if by any chance this might be a cooler water tank, then i'd say get those. I'm thinking the water would have to be very low 70's or mid 60's for them to survive. If you can possibly pull that, then i'd say do that. But to me, its kinda senseless to change your tank to a cooler water tank just to get these snails, you know? And if you've already got stuff, then thats not an option anyways.