Garden Pond Treatment

The healthiest garden pond filters itself. Enough water volume, adequate aeration and a large enough surface area will prevent water quality problems. Larger surface area enables more oxygen to be dissolved in your pond water. According to Casey Coke, marketing manager for Natural Environmental Systems, "...it (dissolved oxygen) is the amount of oxygen available in the pond water. A DO level of 4 ppm to 5 ppm is typically the bottom threshold for most ponds."

A new pond needs time to develop a healthy culture of beneficial bacteria. These bacteria convert harmful substances, such as ammonia, into fertile slurry that will keep your aquatic plants busy producing oxygen for your fish. Stock your pond too soon, and you could experience new filter syndrome--when the beneficial bacteria necessary to convert ammonia and other harmful substances are not abundant enough to meet the load.

Nitrosomonas and Nitrobacter: Working Hand in Glove

Oxygenation and Aeration

It is recommended to construct a pond aeration system which draws water from the bottom of your pond and exposes it to the surface air. This can be a fountain, waterfall, or combination of both. Drawing water from the bottom maximizes the dissolved oxygen in your water. Greater levels of dissolved oxygen increase the speed with which ammonia and other harmful substances are converted.

Things to Avoid

Do not use your ultraviolet water clarifier when your pond is out of balance, especially when you are just getting started. UV water clarifiers kill all bacteria, which will result in your pond becoming more and more alkaline.

Use filtered pond water to clean your filters, not tap water. The chlorine in tap water can wipe out your entire bacterial colony. Wait until late spring or early fall, when cooler weather causes a natural drop in bacterial action, rather than disrupting the cycle mid-season.

Size Matters

A small pond will give you a headache and drain your wallet. A pond less than 3 feet changes temperature more quickly, and has less oxygen capacity. Once water quality is out of balance, it is difficult to bring a small pond back to equilibrium. According to Ben Helm, of Practical Water Gardens, "You should aim for as large a pond as possible, that is at least 3 feet deep. A large pond will help to smooth out any rapid changes in water quality and temperature as well as produce a far more stable pond environment."

Expansion

Base the number of fish you stock on their full-grown size, not their current size. Build additional ponds as needed to accommodate growing or rapidly spawning fish. If you do not have yard space for more in-ground ponds, expand your current pond to include several above-ground refugia. If the slope of your yard permits, build fish ladders between old and new ponds.