What is the best brand or the best deal on a bottom diffused aeration system?

I think you'll get tons of different opinions on this, but the most common answer will be: "it depends." There's currently mixed feelings on the effectiveness of diffused aeration vs surface aeration. I think there are fewer risks involved with surface aeration, and that's what most fish hatcheries use. Lately, with scorching temps in the southern states, people with diffused air have been experiencing fish kills. There's no clear evidence that it was directly caused by the aeration, so that's the big unknown.

Oh okay...I had no idea. Which brands are better?

Aeration can certainly be a sensitive topic. Surface versus bottom aeration is a function of what part of the BOW you want to increase the dissolved oxygen (DO) levels. It is true that fisheries run surface aeration but they don't have the same goals as recreational pond owners. Fisheries are generally doing more to maintain water quality beyond aeration then the average pond owner. Surface aeration is generally best for shallower BOW's and will not provide DO to the deepest part so if the pond is deep it will still be stratified. Bottom aeration will circulate the entire water column and that can be good but it is also what can cause problems.

It is true fish kills can happen and be initiated by bottom diffusion. Bob Lusk had an interesting article on one of the threads posted in this forum in the most recent issue of PB Magazine. One of the conclusions was that it wasn't the bottom diffusion itself that was the problem it was the timing and process that contributed to the fish kill.

If it helps, I have a Keeton KR system. It is oversized for my needs so I have a lot of flexibility and it is "plug and play" so to speak as long as there is power available. I have only had it since June but it runs great and my pond is definitely in better shape than years past when the August heat hit. I am not saying Keeton is the best and it certainly wasn't the cheapest but it is a data point for you. Lots of people have built their own and it seems I have read a lot of good things about Vertex diffusers on this forum.

I did read a lot on the subject in this forum and on line and it was very helpful especially at start-up time. I recommend the same if you are new to it.

Great info Mister A! Thank you!