Sushi never seemed to care that his tank had lots of algae in it, but it's nice to be able to see him and the rest of the tank's contents clearly again. The cleaning was long overdue.
Thanks to guinness_duck for the idea of the glass stones, and seity1 for the suggestion of where to get them, and for also pointing out the river rocks. I think they make a good combination, kind of a water-and-beach effect. I was thinking of tossing the old plastic plants and getting new ones, but the old ones were easier to clean than the gravel, so I kept them.
Maybe one of these days I'll get another snail. I went from five snails to none between last May and this May. I still haven't gotten out of the habit of wanting to pocket a slice of cucumber every time I'm at a salad bar! (Snails love fresh cucumber.)