Anytime you introduce a foreign organic matter that is not created by the system you can expect some algae growth as the biological equilibrium you've achieved has been altered. Just as if you added a new fish. It is important to start slow and increase over time. Problem is that people dose this product or many products like it, and create an imbalance in their tank and blame it on the product, not the fact they just through off the biological balance of their system. With that said Reef Roids is a wonderful product. I fed it with Decapsulated brine shrimp 3 times a day from 2 different feeders. My PO4 would slowly creep up, so I made it a ritual to change the BRS HC GFO every month as regular maintenance. But I would only use 1/4 of the recommended dosage. This would keep my PO4 levels between .01-.05. I would by a Hanna ULR Phosphorus checker to accurately monitor this. Good Luck!