I've been a Big Al's customer for many years now. I've been a customer ever since they were back in their Heritage Drive store in fact. Like most retail in Calgary they suffer from sales people that hide from customers, aren't pleasant or forthcoming with information, etc. If you could replace most of their staff with people who gave a damn it would be a five star store. The staff is so bad most times that I took two stars off.
Their selection is second to none in Calgary and until Big Al's came on the scene Calgary was at the mercy of big box pet stores and a few mom & pop locations scattered around the city. The big box stores had little to no high end aquarium gear and the mom and pop stores would charge your first born! Big Al's provides store and name brand gear for extremely reasonable prices. Sometimes you'll find they're out of line with another retailer and they have always matched prices for me. Their store branded gear is usually pretty decent quality and is magnitudes cheaper than the brand names.
Since moving to their 32nd avenue store their aquaria selection has suffered, but mostly because they've decided to move into dogs, cats, birds, etc. I preferred it as an aquaria only store but it's not stopping me from going there. The fish they sell are mostly in good health, although I have seen exceptions to this rule. I've never seen other animals in distress there as another reviewer stated.