Hi, so wanting to pick up a clean up crew for my 60 gallon frag tank. I see companies offering packs of snails that serve different purposes, seeing as i have a frag tank with no sand and minimal rock, would i benefit from getting a variety of species or just sticking to something like astraea snails? Not too worried about them flipping cause i can easily flip them over in such a shallow tank, was thinking trochus but theyre a little pricey and all the trochus ive gotten in the past havent been able to flip themselves anyway so it doesn't seem like much of a selling point.