Well I have to say I have used Algone for quite sometime now, and here is what happened:
Started using Algone to clear up a bacterial bloom problem, it went away rather quickly and never came back. The tank was perfect for almost a year....then lightning struck!!
I cleaned my Fluval 404 and all the media and hoses....BAM!! three days later the water turned green (algae) and it never recovered! I then broke down and moved the fish after buying another tank to hold them and all the stuff to go with it! And I cleaned the entire tank...EVERYTHING!!! Setup the new tank....using Algone with no fish....Let it sit for two weeks......
Then added the fish...all was right and good in the world...then BAM!!!...same green water!!! I waited using only Algone and regular water changes, for 6 weeks....Still green and fish are dying!!!
I then said "FORGET THIS" and ordered a UV Sterilizer...(Should be here Friday). I wrote to Algone (keep in mind I thought this stuff was the end-all-be-all, so I have a TON of it!) and told them about this and I will post their reply.
So,....my opinion is....if you tank is a little cloudy or you are trying to keep bacterial bloom's away, then Algone is AWESOME! And it does not contain any chemicals (that is why I bought it!)
...but if you are trying to battle a huge algae problem...FORGET IT!!