If the pleco is going after slime coating, I wouldn't be trying algae wafers, instead try a meaty food, such as shrimp pellets, or sinking carnivore pellets.
plain and simple separate the two before your pleco does some serious damage
and the cat is pretty small in relation to the pleco, but that will not be the case in just 2-3 months, if the TSN is well taken care of
get a smaller pleco