Pond Fountains & Aerators

Luckily, there are ways to increase the oxygen in your pond water. But to fix the oxygenation process, you have to understand it first.

Stratification is a process that happens during warm months. When the sun heats the upper surface of water, it causes a layer of warm, oxygen-rich water to form above a layer of cooler water with less dissolved oxygen. Naturally, these layers won’t mix because of the temperature difference. Ever heard that heat rises? The same principle applies in water.

When dissolved oxygen levels become too low, some crummy things can happen in your pond. Beneficial aerobic bacteria that help break down excess debris like leaves, dead plants, and fish waste can no longer survive. So, large amounts of pond muck can accumulate at the bottom. With nothing to break down this gunk, excess nutrients are released back into the water. This can cause algae blooms. And if that wasn’t bad enough, pond muck can also release a gas called hydrogen sulfide. It’s often compared to the smell of rotten eggs.

The stratification cycle is naturally broken during cooler seasons. As the sun’s rays become less intense, air and water surface temperatures cool. Since there’s less of a temperature variance, the two layers naturally mix together again. This process is called turnover.

If turnover happens too rapidly, it can be problematic for fish. Levels of dissolved oxygen on the surface layer may become too diluted to sustain life when mixing with the lower layer that contains very little dissolved oxygen. Basically, as the water mixes, living organisms like fish can suffocate. The good news is that fish kills rarely happen when turnover occurs in nature because the change is gradual over the course of a season.

Installing a fountain or an aerator in your pond can be a good way to prevent stratification. However, if you’re installing these components during the warmer summer and early fall months, be careful. Start by running them in timed increments over the first few weeks so a rapid turnover cycle doesn’t happen. Remember that the purpose of a pond fountain or a pond aerator is not to add dissolved oxygen to the water – it’s to circulate water from the bottom of a pond to the surface. This prevents stratification.

A pond with evenly dispersed dissolved oxygen will make excess nutrients scarcer. But it won’t eradicate established aquatic weeds – unless it’s a species that requires stagnant water like duckweed or blue-green algae. Decreasing the supply of nutrients can slow the growth of new plants, though. And if a consistent supply of new nutrients is still entering the pond, an aerator or fountain won’t be as effective. Other measures such as installing wetland filtration may be a better solution.

If your primary objective is to get rid of unwanted aquatic vegetation, the best solution is usually an herbicidal treatment that should be performed by a licensed applicator. One drawback to herbicide treatments is that decomposing plant matter can deplete oxygen levels from the water, so a pond fountain or an aerator may help maintain healthy levels of dissolved oxygen to prevent stagnation.

No! The more dissolved oxygen in a pond, the better.

Beneficial bacteria thrive in water with more oxygen. And if you have more of these microbes breaking down excess nutrients, algae have less food and the filtration will be more efficient. Plus, your fish will be healthier and more active in a pond with more dissolved oxygen.

Small pond fountains and aerators can be used to keep a hole in the ice during winter months, too. And in larger ponds where fish like grass carp are being used to eat algae, lots of dissolved oxygen will help sustain a healthy population.