Originally Posted by Journeyman
Welcome to the forum!
You'll get some great advice here, and some... not so great.

You're average depth of 8 feet, is a good place to locate your diffusers. Putting them at your deepest holes (12 feet) is ill-advised. Reason being, to maintain some sort of thermocline, for fish health.

You mentioned, loudness and energy efficiency. Those things, as you know, make the Hiblow pump a strong candidate, as does your 8 foot depth.

Your pond would do well with 3 diffusers, I recommend the Matlala. The 1" main line run for that length is good. The HD 200 you mentioned will easily do the job. I run the 120LL, and really like it, costs about 75% less to run than the Gast pump, mentioned above. The LL stands for Long Life, it's has upgraded internal components. This summer marks 5 years without a rebuild for me, it's running 4 heads near the depth you should be running yours.

If it were me running a ditch 600 feet, I'd throw a wire in there for an outlet near the pond and locate the pump there. Maybe add a light post down there as well. The Hiblow is outdoor rated and will withstand the elements, although a small doghouse over it wouldn't hurt.

For late Spring/Summer/Early Fall, running the diffusers in the deepest part of the pond IS recommended, and that is to disrupt the thermocline that has anoxic water in it to promote the aerobic bacteria to work at digesting any accumulated muck. Once the water cools down in the Fall to the 50's or 40's, shut off the deepest diffusers and run the winter diffusers that are in 1/3 to 1/4 the total pond depth once ice forms on the pond. That allows the warmer water (39°F) to stay at the bottom of the pond and create a warm water refuge for the fish.

Since I have never seen any GPH water movement chart for the Matlala diffusers, I'd check the water temp from top to bottom in the pond once it's running for 10 days to see that there is only a few degrees difference in water temp. That will let you know if they are moving enough of the water up to the surface.

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