If you're into building your own things, pond aeration is something you will likely want to tackle at some point.  There is no doubt that aeration is the number one thing you can do to help a pond get, or stay, in better shape.  Doing a DIY pond aerator isn't a complex task and there are some videos now online that talk about how to do it.  After watching some of those however, I came away thinking there was still some useful information that was lacking...and frankly some of the advice wasn't going to work for everyone.  

So in the video below, I go over some of the important aspects of building a pond aerator.  Tips on selecting the right pump, and how to protect it, airline suggestions, and what type of diffuser will work best are included.  

The Pump Or Compressor

The aerator pump, as you might imagine, is the workhorse of the system.  It's what produces the air to power the entire process.  If it goes down or stops working, the whole system will not function...so it's important to pick a good pump for the job that you have at hand.

My main concern with some of the recommendations given in other videos is that most of these are using a kind of septic system pump. These are linear type compressors that use rubber diaphragms to create the air.  This type of compressor is great for certain applications...they are super quiet, and cheap to run around the clock...but they have one major limitation that must be kept in mind.  They will likely not work well in deeper water.  I don't usually suggest using them in anything deeper than 8'.  Some may not work well below 6' of depth...so be sure to ask your supplier what the depth limitations are before you purchase one.  And don't forget your actual depths in the pond too...many will just assume they know what the depths are, but that's not always the case.  

Another issue is you most likely need power pretty close to the pond for the linear to work well long term.  Again, for the same reason that we mentioned depths...as you add distance from a pump to a diffuser, or add depth, you increase the back pressure on the pump.  Push these things too  far and you'll find the diaphragms wearing out much sooner than they normally would.  This adds unwanted down time, repair costs, and ultimately a lot of frustration that could have been avoided by choosing the right pump for the situation.

If you do find you have more depth than 8' or have some distance between your power source and the pond, consider looking at a rocking piston type aerator pump instead.  These are designed to handle depths up to about 50' and we've used them in set ups where power was 1000 feet away from the pond or more...so they can handle a lot more back pressure.

Weather Protective Cabinet Or Cover

Some linear pumps will come housed in a weather protective cover.  Others linears will not, and pretty much all rocking piston pumps will require some protection from the elements.  There are commercial cabinets and covers available, but I have no problem suggestion someone build their own aerator cover as long as the cover is water proof, well ventilated, and kept relatively clean.

One thing to note about the rocking piston pumps.  They do get very hot when they run for awhile...and that's totally normal.  But overheating is possible, and it has happened to some folks who built their own cabinets.  In the end they didn't provide enough cross ventilation to get the heat build up out of the box.  For this reason I suggest a vent on one end, and a small exhaust fan on the other, while leaving plenty of room around the pump for good air flow.

Airline - Non-Weighted or Weighted?

Rubber airline, usually 3/8", but sometimes larger diameters, is used to connect the pump to the diffuser which sits down at the bottom of the pond.  As you shop around you'll likely see some kits available with non-weighted airline.  This is just a type of thin walled poly tubing that has one purpose.  It's meant to save money and keep costs down.  We use it sometimes for the trenched in-ground connection when a pump is quite a ways from the pond itself.  It's cheaper than running weighted airline in the ground.  

However once I get to the water, I only used the weighted airline.  This, thick-walled, stout line will sink to the bottom on it's own and once there, it stays there.  It will not kink, and is extremely durable.  I have found it to be much less of a hassle to deal with over the non-weighted airline...so for the cost difference involved, I find the weighted line to be a good choice for most people. 

Diffusers And Diffusion

The final, key component, of any sub-surface aeration system, is the diffuser.  As the name implies, it's purpose is to take the air from the pump, and turn that air into thousands of tiny bubbles that will quickly rise to the surface of the pond and in a literal sense, break the surface tension of the water.  In doing so, there is a transfer of oxygen from the atmosphere (air), back into the pond.  In addition to this, the rapid rising of the bubbles creates a sort of vortex or circulation, that pushes this oxygenated water, across the pond and then downward again.  In short order, the entire pond is being affected with higher dissolved oxygen levels throughout, better movement and circulation, and less stagnation. 

In simplistic terms there are two types of diffusion that's normally used in aeration.  Course bubble diffusion and fine bubble diffusion.  Course bubble diffusion is very good at mixing the pond water...in other words it helps to create a good circulation of water around the pond.  In comparison, fine bubble diffusion will usually provide adequate mixing, but it also provides much better oxygenation than course bubble diffusion can do.  Better mixing is useful in some industrial settings, such as waste water treatment processed, but for most pond owners, they will do better with a balance of good oxygenation and good mixing.  So fine bubble diffusion should be what you are after when building your own aeration system.

Unfortunately you can't get really fine bubble diffusion without going with some commercial components.  Simply drilling holes in a PVC pipe isn't going to cut it.  As I have often said, any aeration is probably better than nothing, but ultimately for the greatest benefit, you'll want to use a diffuser designed for the task.  The most affordable of these will likely come in a stick form, with a rubber membrane sleeve over the stick.  Other types of diffusers would use membrane plates, or a specialized rubber diffuser tube with a number of porous channels in it.  

Ultimately if your building your own pond aerator, you want something that will obviously help the pond look better or keep the fish healthy and safe.  Aeration also has a good history of helping with algae issues, and it's usually the first thing I add to a pond with problems like this. I think it's great that people are starting to recognize the value of aeration, and in my mind, as long as they are able to source good parts, designed for the task they have at hand, they should be able to create a good pond aerator, that will run dependably for years, and save some hard earned money in the process.