If that isn't enough, add another, and so forth. Ponders also debate the pros and cons of filtering. I found filters more of a hassle than they are worth. At first, you will probably have algae problems until the plants get established. It took me about 3 years to get the pond in an ecological balanced state.
Water is another issue.
Of course, chlorine is a fish and frog killer. Nothing like walking out to check the pond one morning and finding all your fish floating. At that point, I began using well water. But most people don't have that advantage. Dechlorinating chemical work but take time.