Pond Boss Forums AERATION Should I aerate? Aerating a 30 acre "dead lake"

I have a 30 acre "dead lake" in South Alabama that is about 8' deep at its deepest spot stocked with LMB and bream. It is overpopulated with LMB in the 12 - 14" category. The lake is almost an oval shape and gradually gets shallower around the banks. The average depth is probably 5 feet. The lake is limed as necessary and fertilized each year. The watershed is about 100 acres, and well water is pumped into the lake with an electric powered water well during the summer months to keep the pond full. The water level drops down about 2' for three to fours months if the well is not used. The problem with using the water well is it creates an algae bloom I assume from whatever happens to the water chemistry when all this well water is introduced. We have a fish kill about every 5 years or so. We have also stocked the pond with Sterile Grass Carp that helps a little but doesn't solve the problem.

I have two questions. One is will aeration help prevent the algae bloom, and the second question is can I get away with not pumping in well water during the summer months and just let the average depth of the pond lower to where the lake has an average depth of about 3'? This lake has produced LMB in the 5 - 8 lb category consistently in the past as well as very large bream (over 1 lb.), but inevitably there is a fish kill that negates all the efforts.

Thanks in advance for any thoughts/comments.

I read your message. I don't think that I can help you becuse I do not have enough aeration experience of larger ponds and southern ponds. I replied just to let you know I did not ignore your question. I just have lack of experience and cannot provide reliable or good basic knowledge about your problem. I have my opinions but not enough experiences to put my money where my mouth is.

g-8, Let me see if I can get Cary Martin our aeration manager for Vertex Water Features to ring in on this one as he is accustomed to large southern waters. Ted

You sound like you have over built your water shed GREATLY for the size pond you have...I have some experiance with people doing this...have you ever thought about reducing the size down the a more 'managable' size? like 10 acres...

When you say "algae bloom" what kind of algae are you talking about? Grass carp don't filter out plankton algae so are you talking about string algae? I hear it takes a lot of carp to eat string algae.

g-8-outdoors, If I read your request properly, you have actually have three questions.

Question 1: "will aeration help prevent the algae bloom?"

Some ponds age quicker than normal. This usually due to low assimilation ability of the pond. In other words, there are not enough beneficial organisms to consume the ortho-phosphates, nitrates, and other nutrients that are entering the pond from your watershed and from your well. You may even be feeding too. This is due to low oxygen levels typically found at the bottom of the pond.

By increasing the oxygen levels from top to bottom, an organism (zooplankton) now has a larger area to feed. Zooplankton is one of the largest consumers of plankton algae in a pond. They are also the basis of the food chain for fish.

Also, once an aeration system is installed in a pond, the oxygen levels are raised at the bottom, the habitat for beneficial bacteria (aerobic bacteria) and benthic organisms (slugs, snails, mussels, worms) will begin to move throughout the entire pond bottom and begin to consume that muck layer.

Other things happen to help limit the release of nutrients in the water column. One measurement we use as Limnologist is called the Redox Potential. This is a measure of the proportion of oxidation to reduce substances. In a pond that is low in oxygen or (anaerobic) the redox typically is in the negatives. Once we aerate, the redox now turns to the positive thereby bonding the orthophosphorous and nitrates to the bottom of the pond and limiting the release for the algae to use as a food source. Also iron found in the water column will precipitate out of the water column and act as a blanket on the bottom blocking the release of these nutrients.

In summary, by adding an aeration system we have now increased the pond's ability to assimilate the nutrients that are washing in.

Question 2: "Can I get away with not pumping in well water during the summer months and just let the average depth of the pond be lower to where the lake has an average depth of about 3 feet"

Answer: I would recomend keeping as deep a water depth as possible to a) reduce the depth by which the sun can penetrate thereby reducing the plankton algae's ability to produce chlorophyll, b) to limit predation by birds. With that shallow of a depth, you could find that you loose more fish due to avian predation.

The algae bloom found when you run the pump is due to the combination of as stated above, accessive nutrients washing in from the watershed and the internal nutrient loading from the well. Again, the lake does not have the abilty or capacity to assimilate those nutrients due to increased anoxic areas in the bottom. Aeration will aid in elimnating those problems.

Question 3: "We have a fish kill about every 5 years or so"

Answer: I know that this is not a question, but I am sure you want to elimnate the possibility of any further oxygen related fish kills.

Aeration will eliminate this. That large algae bloom you spoke of will generate large amounts of oxygen during the day at the surface. At night, that same large algae bloom will respirate and consume that same oxygen. That action combined with the lack of oxygen found at the bottom and the fact that the fish & bacteria need oxygen during the night too will drop the oxygen levels so low that the fish are unable to survive.

Just from the limited information you provided on the size in acres of your lake and the average depth, (6) well placed AirStations will solve these problems for you. Please feel free to contact me to discuss this further. I feel this forum is spectacular for information gathering and question answering, but I also would like to make sure your concerns and questions are taken care of.

I look forward to hearing from you.

Ted, thank you for bringing this to my attention.

Fish kills are a fact of life in arid areas when pond owners fertilize. It sounds like a good idea to increase carrying capacity but when the almost inevitable summer evaporation occurs, the pond is overstocked. Overcast, non windy days then beget fish kills. This brings about my question/thought. You indicate that you lime as necessary and fertilize annually. That might make sense in area of low alkilinity. However, is it really necessary? The fish kills and algae might be indicators of fertilization problems when you have an annual 40% drop in carrying capacity. Adding non-oxygenated well water might exacerbate the problem. If your water quality doesn't really require chemical alteration, the mechanically supplied oxygenation could do even more good on helping clean out the muck (I guess). I don't know much about aeration but have gotten a pretty good handle on the dangers of fertilization when the water level varies seasonally. I followed the prescribed fertilization routine for the first couple of years that I had my pond. Had fish kills both years. I stopped fertilizing and the overall biomass was apparently reduced a little bit but the fish kills absolutely stopped. I also have no weed problems like everyone else. Think it over. Gotta admit though, I'm not producing any 5-8 pound bass yet.

I can't tell you all how much I appreciate your input. The lake is a natural lake and has probably been around over 100 years so there is unfortunately no economically feasible way to reduce the size. I'm thinking aeration and no fertilization may be the right approach unless someone thinks otherwise. The overall biomass will not be a problem since we can't catch enough anyway at this point. It is not uncommon for three of us to fish for three hours and bring in around 90 LMBs in the 12 - 14" category. We do not provide supplemental feeding, and the algae I described is filamentous - the green slimy kind. The carp help but can't keep up with the rapid growth. Maybe the aeration will produce a greater area for insects/terrestrials to survive that provide food that didn't exist with fertilization. Any thoughts? Thanks

I have a "dumb Yankee" (as opposed to "damn Yankee," hopefully) question: What makes this a "dead lake?" I am unfamiliar with that term with respect to a lake that holds a population of fish.

Not a stupid question at all - it's simply a figure of speech we've always used in "L.A." (Lower Alabama that is). The 30 acre pond is situated in a 100 acre "bowl" so to speak. Once the rain water or water from our electric water well comes in there is no way out - except for evaporation/seepage that is!

How can your lake be natural and only 100 years old? I thought natural lakes were thousands of years old formed by geologic activity of some sort.

Layton Runkle

G-8,

When you posted ...three guys fishing three hours catching 90 LMBs, I'm thinking how many folks on this board would like to have a stringer like that to brag about. Thanks for the definition.

Russ

Here in Wisconsin near me are a few shallow lakes with occasional fish kills. I have found that if the lakes can go for three or four years without one that the fishing is really good. THis is because of the high percentage of litteral zone which allows the food chain to pump higher than on the deeper lakes. Also, any fish left after a kill have reduced competition, which results in great growth rates. Fish populations quickly recover as well. I would imagine with fertilization and aeration, that growth rates would remain high. A lake manager from the area should be able to customize a management plan to produce a trophy environment.
Robert B

Your lake sounds rather shallow at 5-8'. Also Working against you is going to be the water temperature during the summers due to your location and the depth. This creates a less than stable eco environment.

I have a suggestion I hope you try before next summer. Contact a good experienced Biologist (See one link below) and get their advice after a complete testing of the lake water, well water, soil in the lake bed and soil in the run off area.

There very effective ways to control algae without spending the money for aerating a 30 acre lake. Find out all the facts before you throw money at it.

http://aquahabitat.com/pondering.html

http://www.dirtdoctor.com/view_question.php?id=761&set_theme=1

Scroll down to the Corn Meal section at the above link for more information.

I am familiar with your dead water concept. I have two ponds on my property that would fall into that category that I do not have any problems with thanks to some initial testing and corrective steps.

One extreme example of dead water is at Green lakes state park near Syracuse N.Y. Plunge pools from glaciers left lakes that were up to 80' deep. There is practically no turn over of water from the bottom of the pools and there is virtually no significant aquatic life in them due to the lack of dissolved oxygen.

Algae is not all bad all the time.

Good luck

JW