Hi,
I would recommend the BM220cs for a heavily populated tank.
Yes BM do cover our claims if there was one, but only cover OUR claims, they have records of our purchases and if i tried to claim for a product we did not buy from them they would ask us to refer the claim to the distributor that did.
Walk into he sony store and ask them warranty a tv you bought at walmart and see what they say?
same policy really.