My Dolphin was constantly getting stuck on both drains in my pool, usually several times per cleaning. I bought 2 Polaris unicovers back in May and they've been working great- the Dolphin goes right over them. I did have one time when it somehow managed to move one of the covers off the drain, but that seems to have been the exception. I think they were way over-priced at $59.00 each , but at least now I can drop the Dolphin in overnight and wake up to a clean pool. I bought mine from In the Swim, but I'm not sure if they ship to Canada.

Hope this helps.
-Steve