Pond Boss Forums Thread Like Summary - When are multiple airstations required?

New re-dug pond in progress, and I am trying to size and shop for an aeration system. Below are sketches and data of the pond at the current water level and also an estimate when (if) the pond raises 3 more feet to full pool.

To measure area, I approximated the pond shape as a semicircle + trapezoid.

To measure volume, I strung two ropes across the pond, AB and CD. At 10 ft intervals along each segment, I measured water depth. I then took the average of the measurements. The deepest hole is not in the center of the pond but biased to one end.

So, my questions are:

1. How many airstations are needed? I know about the rule of thumb calculation of 1 to 2 volume turnovers per day. This requires the volume of water lift created by the diffusers. Only Vertex seems to offer this data, however. Since the deep hole is not centered, my hunch is that two diffusers are needed - one in the deep hole, and another somewhere along segment AB.

2. Rotary vane or rocking piston? I know this has been discussed many times before, but I'll ask it again. A rotary vane would probably be sufficient since the water depth is less than 18 ft. However, rocking piston compressors seem to be much more popular in the commercial systems that I am browsing through.

Thanks!

Here's what I remember about them. All have occurred in my larger, older pond (2/3 acre, dug 2001).

One (the first ???) happened shortly after ice out. It killed (based on corpses) only large sunfish - I recovered about 6 dozen large (8"+) BG and about one dozen large RES. No LMB, CC, or GC were affected (no corpses and no apparent reduction in numbers). I discussed that one here at length, and no good hypotheses were developed - even Bob Lusk was at a loss as to why it happened.

I had kills two years in a row (the first major, the second minor) in the second half of September, which affected large fish of all species. I believe they were attributable to low Oxygen levels that developed when water cooled and a (fairly) large % of warm water plants died and began decaying. Following these, I have upped the hours I run my aeration system each day starting on September 1, and have had no more mid-September dying events.

About five years ago I started having the pond treated regularly (every two weeks at first, now once a month) for excessive plant growth after a year in which coontail filled an estimated 80% of the pond's volume. (Fishing was impossible, I stopped feeding, and was scared to do anything except run a lot of aeration. Fortunately, the fish made it through that year okay.) The next fishkill occurred a few years later the day after a rookie pond treater showed up (first arguing with my wife that they knew where the pond was and she didn't) and treated the pond with something (God only knows what or how much) without running a preliminary inspection to see what might need controlled, the way every other pond treater from this particular company has since day one. Large fish of all species were killed, including my wife's beloved Paddlefish (she think every BOW should have a monster). The pond company sent the rookie back to pick up all the carcasses (karma) and report on what was killed (this genius "found" dead YP, which have never been in that pond, and dead Walleye, which have never been here in either pond). The company and I negotiated over the loss and they restocked all lost (recovered, actually) fish numbers and species (that were actually present - no YP or WE) in as close to the lost sizes as was possible (which is how I have seen $2000 worth of LMB). (The rookie no longer works for them, and I have been satisfied and usually quite happy with their services for a long time, so I am refraining from mentioning who they are).

Last year I had another low Oxygen kill in mid-Summer, which my experienced (BS & MS in fishery management) pond treater and I agreed was caused by nutrient buildup (heavy feeding for 20 years, a large fish biomass, and cattle pasture runoff) and subsequent plant growth. This Spring I had the pond Phoslock treated; I am running aeration more than in prior years and keeping my fingers crossed. I am keeping future additional Phoslock treatments in mind as possibilities.

Overall, I believe I have met Bruce Condello's definition of and Aquaculturist, someone who has killed over a million fish.

1/4 acre pond here.

I'm running 1/4hp rocking piston with one diffuser in the shallow end of my pond, it runs 24/7, it looks just like yours. I also run 1/2hp rocking piston with 3 diffusers in the deeper areas of the pond at night when the air temps are cooler overnight. My pond is long and narrow and a single diffuser running in the center left areas on the ends not covered. I have very green water which makes my pond susceptible to DO sags, current secchi disk reading is 12-13".

I've seen quite a few fish kills, with a DO sag I've noticed that fish like to move shallow, I've seen 16"-17" SMB park their nose as shallow as they can get with their top fins out of the water. I've seen 30-40 15-16" LMB swimming in a school back and forth along the bank in two feet of water ignoring people standing on the bank.

During the summer I will turn the 1/2hp aerator on during the day when we have cloudy rainy weather for an extended period of time.

Watch you water color, if your water goes from very green to brown, you might have a DO sag in process.

If it were mine (it is not too dissimilar in size and shape from my 2 ponds) I would put a deep water diffuser in the hole and a shallow water diffuser near the shallow (top in the images) end. I'd run them both in the Summer and run the shallow one selectively, as needed, in the Winter to prevent Winterkill.

Note that my methodology has only had about 5 fishkills in 38 pond-years.