Scum on Pond

[baker_eliz]

Hi. We have a country house (not our primary residence) in Northern California, cantilevered over a pond with approximately 325,000 gallons of water. We had not been there for a few weeks, during which there were fairly heavy rains. We checked out the house for damage recently, and the pond is covered with a thin greenish-brown (khaki green?) film. We have never seen this film before.

The house and pond are in a draw, so water from hills on all sides drain into the pond. Behind us, our neighbor(s) has commercial organic gardens, so the pond does get some runoff from their fields.

There are approximately 15 large koi in the pond, none of which we saw but they are generally at the bottom of the pond this time of year.

Any idea what this film could be? And is it dangerous to the koi?

Additionally, elodea from a fishbowl a child dumped in the pond 30 years ago is trying to take over the pond, so any ideas for this would be appreciated, as well.

--elizabeth

 

[j.w]

Elizabeth
Could be fertilizer run off from the gardens. Even if organic he still prolly uses it and might also be helping that Elodea grow so well. Just guessing at this. You'll have to do water testing to see if anything is going on that might hurt the fish.

 

[mtpond]

Welcome Elizabeth.

 

[addy1]

Welcome to the group! Most likely the run off is causing the muck.

 

[sissy]

If it is organic farm they use no fertilizers but use compost and manure to treat the soil like my dad did so you are getting a lot of organic matter from the extreme nutrients in the ground and that cause a burst of it in the pond .It will pass as every once in a while it would happen to our pond at my dads house in NJ .It can cause some problems with algae growth and plant matter growth but there is nothing you can do .Compost and manure are natural and will break down over time .Thats why farms now have to protect farm streams because they run into larger bodies of water .The Chesapeake bay here is a great example of it and have had problems with farm runoff for years and have started a bill to try and stop farm run off .My father had to put up the black run off barriers like builders use .

 

[baker_eliz]

sissy, is the "burst" you get in your pond a kind of khaki greenish-brown?

 

[sissy]

that was my mom and dads pond and that house was sold a long time ago and yep I use to have to skim it off and I would put it on plants and boy would they grow .My father would treat the pond with something he would buy at the farm store .If you look on you tube and find how they make manure tea to fertilize plants you will see the scum .They put manure in a bag float it in water and add an aerator to force air all around it .It makes the best fertilizer around .My father would sometimes put a pump in our pond and pump the nutrient rich water out into the gardens and boy what a crop of veggies we would get .Then he put a gallon of the stuff he got in the pond to cut the rest and rains would help .My father was an organic farmer when organic was not a buzz word and that was almost 30 years that he sold the farm to retire .I used to call the foam ooze ,it looked alien to me .Can't remember what he bought to cut the nutrients with since it was so long ago and I know he used to add salt to the pond also .We just had turtles that hung around and frogs and minnows in the pond and seemed to never harm them .He also had a big test kit he bought from the farm store .I used to have to run around the pond with a bucket to take samples from all over .Not sure what he was testing for ,I never asked him .I guess it was similar to the pond test kits we have now but on a bigger scale .My dad was always concerned about all that stuff

 

[baker_eliz]

UPDATE: We are still having problems with the scum/algae. We no longer have the elodea, but now this year we have new grasses in the pond. The new grasses don't seem quite so invasive. You can see from the attched pics that the pond is quite large. It's about 12' deep in the middle. There is some slight runoff from the neighbors, it's true, but their olive trees are over the ridgetop from us and runoff from rain and their irrigation would run down on their side of the hill, not ours.

Anyone have any suggestions on how to deal with this? Any tests we should run? We have a pump that runs for about 30 minutes every morning to oxygenate the water for the fish, but that's all we are doing.

Thanks, everyone, for your help.

 

[peter hillman]

Hmmm, I'm thinking you need to run that pump closer to 12hrs, that water looks stagnant.

 

[Lisak1]

I can't help with your scum problem - looks like dead algae to me - but i just had to say your home and pond are gorgeous!

 

[baker_eliz]

Hmmm, I'm thinking you need to run that pump closer to 12hrs, that water looks stagnant.

That sounds like a long time, Peter. It's a 1/3 hp pump. I'm not sure our electric bill could handle that. And would we need to run it in the winter?

 

[baker_eliz]

I can't help with your scum problem - looks like dead algae to me - but i just had to say your home and pond are gorgeous!

Thanks, Lisak. My boyfriend's family built it themselves in the late 60's (if memory serves me). They camped out in tents on the hillside for six months while building it; his French mother cooked gourment meals for everyone on a campstove!. My boyfriend was the electrician and plumber. They had one family friend help who actually knew what he was doing! The pond was actually constructed by the Corps of Engineers; apparently, after World War II, they went around the countryside and dug ponds for all the ranchers.

 

[peter hillman]

We have a man made lake in town that suffered for years, fish died, ducks n geese died. Then, they installed three aeration fountains and within the year the water was clear and full of life. Try to look into some lower power consumption pumps, air pumps would work well for you.

"Last year the city installed a water circulation project to improve the quality of Virginia Lake's water. Since then, experts say the water clarity has improved.

The City of Reno says a new underwater pipe is one of the many things that has helped circulate the water. Measurements are showing a big difference.

Lynell Garfield, a hydrologist with the City of Reno said, "Last year with the extreme drought, we saw four to six inches or so of depth, where you could drop the disk in before it disappeared. And this year it was well over 7 feet."

Garfield says that's a dramatic improvement in water clarity. In the past couple of years, algae has grown and toxins were killing off a massive amount of birds.

The lake was stagnant year round, but with the new outlet constructed, it's now forcing the flows from north to south to better circulate the water."

 

[Meyer Jordan]

Running a pump alone will not cure your problem regardless of how long you operate it.
It is quite obvious from your photos that you pond accumulates a considerable amount of organic matted. The leaf drop alone is quite heavy not to mention the run-off that you certainly get. Much of this settles on the bottom of the pond creating anoxic conditions in the deeper areas .Add to this the tannins that are leached out clouding the water, reducing clarity and subsequent good algae growth. This greatly retards photosynthesis also reducing Dissolved Oxygen levels. Because the Oxygen levels are below what would be desired or normal, the bacteria that would normally consume/degrade the accumulated sediment are unable to function. The ultimate breakdown of this sediment takes considerably longer and those nutrients that are released through other actions are left to be consumed by planktonic and semi-planktonic algae.
Bottom line is if you want to correct your problem, Oxygen levels need to be increased across the entire water column especially in the deeper areas of the pond. This can only be adequately accomplished through the use of diffuser aeration. The cure does not happen overnight but it is a gradual improvement until good water clarity is restored.
Pond/water treatments will do little to combat your problem and may actual exacerbate it.

 

[baker_eliz]

Thanks, Meyer and Peter. It sounds like aeration is what is needed. My boyfriend had been hoping the pump he installed that shoots a strong stream of water into the air would induce enough oxygenation, but obviously not. We just looked online and it seems a pump for an acre-foot pond, which we estimate ours to be, runs around $700 (which is why he was dragging his feet about getting one). Do either of you (or anyone else who wants to chime in) have a recommendation for a pump and/or sourcing one? And how long, how often, and during what times of year would it need to be run? Thanks so much for your time in answering and your suggestions.