my tank was bein over run with diatoms i beleive so i ordered a clean up crew and got it yesterday.. it came like 25min. before i had to leave for work so i started floatin the bags as soon as i could and when my wife came home i filled her in on how to finish the process.. i got 10 Astera, 10 Margarita,5Cerith and 5 Nassarus snails and a replacement Peppermint Shrimp for the last one that didn't make it.. happy to say the snails are doing their job great! i can see most of the rocks again.. they were covered in what looked to be dust? guessin that was diatoms.. the peppermint on the other hand.. hes kinda hiding under a rock on the very bottom of the tank just swayin back and forth not eating any apista .. hopefully he will come out of hiding and get to work! do you guys think 30 snails is over kill for a 55g? i think i got a good price for em only paid 40 shipped.. what else will eat apista? hopefully my camera comes monday because i have alot of stuff i want ID'd and with a good camera it will be alot easyier for all of us lol.. ,