I think adding bacteria is just a way to get you to spend money. With a biofilter, the bacteria grow in a few days no matter what if there is organic stuff in the water which you will have if you have added plants and or fish. The bacteria will then always be there in the water if you don't change all of it.

I've taught microbiology in college. I can assure you that if you have a culture of live bacteria that are capable of growing in your pond, you only have to add them once -- not twice, not once a week -- just once.

Many people question whether any of the expensive "bacterial preparations" contain live bacteria, but to me the instructions to add them repeatedly says clearly that they don't.

Any bacteria that are useful and are capable of growing well in your pond will wind up there within a month or so, provided that you don't put a bunch of crap in your pond. My definition of "crap" is anything other than dechlorinater and a little fish food.

If you have access to a healthy pond, you can transfer some water into your new pond, giving it a bacterial head start.

I agree about the absurdity of adding bacteria over and over. Like the "colon health" capsules that are supposed to contain millions of live bacteria, but want you to take them every day.

Thanks for all the advice. I also read that a uv light will kill bacteria. My filter does have a uv light on it. Will it harm the beneficial bacteria that develop?

Yes, UV will delay the establishment of your nitrifying bacteria. Many people think it won't because these bacteria grow on surfaces and thus won't be flowing through the UV. However, when the bacteria divide -- which they must do to get a large enough population to detoxify your water -- typically one of the new bugs stays in place and the other floats off to land on unoccupied space. If it goes through the UV before it finds that spot its a goner, and the cycling process can be greatly prolonged.

If you really want to add bacteria, put in a little good soil from an organic garden or from a compost pile. These will have a good supply of nitrifying bacteria.

It's easy to get your pond ecosystem started if you just start with one or two little fish, feed them lightly every other day, and don't add anything that comes in a bottle except dechlorinater.