I don't have any good pics of the whole tank... I should do that huh?
I used a window screen repair kit... it's about 20 feet worth of fiberglass window screen, about 30 inches wide, cut to fit the top of the tank. I seperated the glass lids and only used half of them to hold the screen down firmly, and then just duct tape the edges to the top of the tank. As my octopus grows larger I'm going to reinforce it, probably add more weight, and add velcro around the top of the tank. The rough feeling of the velcro deters octopuses because their suckers don't stick to it, and it's rough on their skin.
I bet someone on TONMO could tell you how to get one in Canada.