I wasn't trying to say that they produce a lot of waste, just that they will add to the total waste being produced, in a tank that cant handle the load to begin with. And unless other measures are taken, besides CUC, it will only get worse.
I have a small CUC in my tank, and their purpose is to help prevent high nutrient levels by scavenging uneaten food, and hopefully avoiding algea outbreaks and poor water quality. Not to take care of a problem once it already exists
I did suggest to the OP that a couple Emeralds would help with the algea. IMO
there are just more important things to be done to help prevent it in the future ( less food, regular water changes, monitor phosphates)