Minor maintanence is needed to keep any pond clean and healthy. After the first year, the pond was drained to inspect the liner. For this task, a Sears shop-vac worked wonders.

Most water garden books recommend putting plants in pots with holes (the ones that look like drainers). Put plants in solid plastic pots instead. Otherwise, the roots grow through the holes, pushing all the dirt out and into the pond.

Refill the pond, and reintroduce the fish slowly one at a time so if something's wrong, the whole school won't be lost.

After the first year, the pond should establish a healthy eco-system, so further drainings are not necessary. Just keep the filters running clean, and take care to remove junk/debris that accumulates in the water.