HoneyHole provides the standard suggestion by F&W agencies/Co-Op ext/ fert manufactures etc. It is good general advice and works well for many. Keep in mind that every pond is different and it is wise to start slowly until you have personal experience with that pond. I have seen many ponds that don't need fertilizer. Many others would go to less than 12 inch vis using the standard suggestion in a few days. That can cause an O2 depletion and fish kill. Know your pond first because it all depends. I use less than 25% of the suggested amounts and get good blooms (sometimes to good). If I used the suggested rates I would have a disaster.