Weekend Feeder Tablets

Had 2 snails and a golden algae eater. Perfectly happy and relatively healthy, still cleaning away, but more algae left to eat. Also put a few wafers in the tank on Thursday. Went out of town Thursday afternoon and stuck in a 3 day weekend feeder tablet. Came back on Sunday afternoon and had 2 dead snails. 2 weeks later, the algae eater in happy and healthy. Wondering if the snails could have been killed by the weekend feeder tablets. Trying to figure out if I'll be able to get more snails and use weekend feeders or what might else might have killed them that fast. Thanks.

 

Accidentally posted this on the Saltwater side first. My bad.