This concrete drain cover has all the advantages of the standard drain cover plus a built in air diffuser for aeration.

Installation Instructions – Link

Recommended Alita Air Pump For Advantage Drain Cover with Air:

Placement Depth of Drain Cover	Operating 1 Drain Cover	Operating 2 Drain Cover
1 to 5 Feet Deep	AL-40	AL-60
6 to 8 Feet Deep	AL-60	AL-80
8 to 12 Feet Deep	AL-80	AL-150

Even without a bottom drain, many use these purely as air diffusers as they are easy to install, very reliable, and heavy enough to remain stationary.

At 22lbs the Advantage Concrete Bottom Drain Cover with Air Diffuser is much too large for any koi to move out of the way. The 3/4 inch legs prevent any large sinking debris from being sucked into the bottom drain, while still allowing for the maximum amount of flow. The main advantage though is when it comes to maintenance. With the Advantage bottom drain cover, you can easily use your net to push aside the cover, net up the sunken debris, then finally push the bottom drain cover back into position. All the while keeping your fish happy and healthy in a highly aerated pond..

When used for aeration only:

These Bottom Drain Covers can be used very effectively to add oxygen to any pond, with or without a bottom drain. Because of their weight (22 pounds) they will usually stay wherever you place them in the pond. For that reason, proper placement in the pond is important. Here are some things to consider:

Usually, placing the air dome in the deepest area of the pond will give you the most amount of circulation and oxygen. Avoid placing the cover near the skimmer area if possible. The air dome when operating will create so much turbulence on the surface that it will prevent debris from reaching the skimmer. Placing the air dome at the opposite end of the pond will push debris toward the skimmer; often time making the skimmer more effective rather than less.

If you have a major “dead area” in the pond where the water does not circulate well it can contribute to poor water and lack of clarity. By placing an air dome in that area you can cause that water to begin circulating normally and at the same time greatly increase the oxygen in the pond.

In order to install this drain cover in a liner pond, you will need the following adapter: Bulkhead Adapter