I kept them for about 4 years and did not have algae break of cladophora algae. Their growth rate is very slow, and they should be turned every now and then to keep their growth even. Snails, ottos, plecos and any other algae eater I ever heard of do NOT eat these. Shrimp do like to eat the microorganisms off them, but not the algae ball itself. They do well in low to high lighting and are extremely easy to care for.