I run them on my 46G Bow front with great success. Rule of thumb is to start with small amounts, very small, it takes several weeks for them to start working. Add small quantities over time pending on the demand of your system. IMO you should resolve the cyano issue before adding the pellets. I run a Reef Octopus BioChurn 90EXT HOB, it's rated for up to 100 gallons. Considering I have it on a 46G bow front, truly a 35G system, I only run about a fifth of the pellets that it can hold. Less is more.