Pond Scum

[EBS]

My son has a 2-3 acre pond (tank) on his place near Paso Robles, Ca. The fish population of bluegills and bass is healthy. There is also a healthy population of green filamentous algae around the shoreline (except along the dam where the drop-off is steep). By the middle of summer the algal bloom forms an unsightly and smelly layer of gas-riddled scum extending 15 feet out from shore. I'm interested in any thoughts about control of this phenomenon. I read the BB discussion about aeration with a windmill driven system, but it mainly focused on the technical issues, not on control of pond scum. I've looked at several web sites advertising various biological, chemical, or mechanical methods to control algal scum, but most look either improbable or too good to be true.
My son's interested in a pump driven aeration system, but I remain skeptical. Do any of you all have direct experience with successful control of pond algal scum by methods that are both affordable and practical? I would appreciate any thoughts.
Ed

 

[theboman]

I think I saw pumps at Harbour Freight (harbourfreight.com) that can be used to circulate the water, actually create a fountain! This should help a whole lot. The pond needs the water to circulate. Notice you never see the scum in rivers, the ocean, etc. It's a one time price and a small electric bill as opposed to chemicals each year.

Bluegrass, Pick It Up!

 

[fishman]

EBS,

The most common cause of filamentous algae is a seasonal influx of nutrients. The first thing I would do is see what kind of land practices are going on in the watershed. Does your son or his neighbors have livestock? If so, that is the root of the problem.

For the cure, I would suggest that your son talk to the local fisheries biologist. They would most likely be aware of methods that are successful in his area. A lot depends on how deep his pockets are, or how much time he is willing to devote to his lake.

If I were making a recommendation for a Texas lake in that condition, I would likely recommend fertilization and installing an aeration system. I would not recommend this if there were livestock that directly accessed the lake, or if the landowner didn't want to spend the time and money. Fertilization "evens out" the availability of nutrients in the pond and allows beneficial (single-celled, non-connected) algae to grow, outcompeting the opportunistic blue-green algae, and giving your pond a pleasing green tint. Aeration prevents fish die-offs in the event of an algae die-off that causes dissolved oxygen levels to crash. If your son gets the go-ahead from his local biologist, and you want specifics on the type and amount of liquid fertilizer to use, send me a message.

A short-term solution would be to apply Cutrine-plus, which is an algalcide. Follow label directions, and don't treat more than a third of the pond at one time to reduce the possibility of fish kills due to low dissolved oxygen. I would recommend AGAINST using copper sulfate, as it is persistent in the environment and can cause a host of problems later on, from increasing algae presence, to inhibiting fish reproduction. Cutrine-plus contains copper also, but in much, much smaller doses.

Please don't take this information as any more than a guideline which may suggest some questions to ask the local California biologist. I don't know, but they may come out and assess his problem for free. Here is a link to their web site:
http://www.dfg.ca.gov

Good luck!

 

[ChrisR]

Hi Ed

We have a lot of problems over here in Western Australia with algal blooms, some are extremly toxic, and can choke the life out of waterways. I've given a site that provides info into them, hopefully you may find something of use.

http://www.wrc.wa.gov.au/public/waterfacts/6_algal_blooms/index.html

Regards

Chris

 

[DaveM]

Hi Fishman,

First off, thanks for your informative message! It leads me to a couple of questions I wonder if you might shed some more light on. Would goose feces qualify as a "seasonal influx of nutrients"? If this influx is not repeated will a small growth of filmentous algae die off after a period of time, say after a hard, cold winter?

Our small, 3 year old pond developed some of this algae late this past summer after being occupied by 5-6 Canada geese. It was also a very dry summer and the pond level dropped about 4' from it's spring time high mark. Recent heavy rains brought the level back up by about 1.5' and the algae is currently too deep to see. The pond is aprx. 90'-100' in diameter with very steep sides and about 12' deep when the water level is at it's highest point.

Thanks Again- Dave

 

[fishman]

DaveM,

Yes, waterfowl are a big culprit in many pond algae problems, particularly non-resident birds. What happens is that they show up to nest in late spring and began doing their thing, and then leave in the fall. This is true in the midwest, that is. In contrast, if available nutrients are increased in EARLY spring, that gives the beneficial algae time to reproduce and get a jump on the undesireable filamentous algae. I have seen ponds with resident birds that do fine, because the birds poop year round. It's that sudden influx of nutrients that benefits opportunistic species like filamentous algae.

I am a little uncertain from your discription if you have a problem with filamentous algae or with a rooted plant. You state <font color=blue>"the algae is currently too deep to see"</font color=blue>. If it is filamentous algae, it usually either floats on top (not attached to the bottom), or it dies and sinks to the bottom. If the plant is rooted to the bottom it is something else entirely. The treatment I would recommended for that would be triploid (sterile) grass carp in appropriate numbers (NY law permitting, of course). If the vegetation is not causing you any problems, it might be best just to let it be.

If you have pond questions, you probably should call your local fisheries biologist. They are familiar with your region and can be very helpful. Your results may vary of course./w3tcompact/icons/smile.gif

 

[DaveM]

Thanks again! I'm not 100% sure it's filementous algae but the name sure sounds like a good fit. It has the look of cotton candy... only green in color. It is attached to the bottom and was just beginning to reach the surface and flatten out when we got the rain and water elevation. My thinking (and hoping!) was that once the water returns to it's highest level next spring and if I can keep away next spring's geese that this stuff might just die away without my intervention.

And yes, I need to find out more about my local fisheries and other wildlife officials!

Dave

 

[Anonymous Poster]

Here is a site that may offer some assistance. PONDBOSS.com Click on "Ask the Boss".


Russ

 

[DaveM]

Thanks Rus! I'll check it out.

Just remembered I took some photos the other day. Fortunately (or unfortunately!?) no scum is visable in this shot. Our house is kinda visable in the background.

Dave

 

[fishman]

DaveM,

That sure is a pretty place you have there!

Yes, if you can keep the geese away, you should be in good shape.