So warming up here finally and here comes the algae mats. Last year during the worst of it lost all my large bluegill. So I know how to attack it when it shows with spraying - but can you get to the root cause ahead of time (which I presume is nutrient load) and stop it before it appears?
1/2 acre pond 11 feet at deepest part, bass and bluegill and five 15+ lb. grass carp. Frequented by Canada Geese November- May. Lawn irrigation is done from the pond everyday and approx 6500 gallons of fresh 70 degree clean river water is added every day.
Canadian Geese might be one major source of your excess nutrient load.
Their excrement in the water, and on the banks where it will eventually run into the water, is excellent fertilizer for your algae.
I don't know the rules in Oregon about harassing the geese (or your family rules), but fewer geese would probably help substantially with the algae.
Adding more aquatic plants (non-spreading or minimal spreading) would also help some, as those plants take up nutrients, that leaves less available for the algae.
There are effective algaecide chemicals that might work for you. Especially since you can add supplemental river water as the decaying algae depletes your oxygen. However, you need to remove the algae after killing it, or the nutrients soon go back into the next growth cycle.
Tilapia are also becoming a useful algae treatment tool. You might check their legality and availability in Oregon. The carp do not eat the algae, the tilapia do. They then will probably die off over the winter, and you will have to re-stock them every year. But they will reproduce quickly during the warm months and some people on the forum have had good success with them.
Finally, just raking/netting out the mats has some positive value. Throw the mats somewhere such that the nutrients will NOT wash back into the pond.
It took a lot of research, but here's something to think about.
One goose will poop enough in a pond in ONE day to grow 115 pounds of algae. I'll let you do the math. Also together 10 geese make the equivalent manure of one cow. That is a lot of fertility for a pond of any size and it is especially problematic for a small 1/2 ac pond. This is partly the reason for the greenery. Once in the pond the nutrient fertility has no way to get out unless you harvest something that grew in the pond. Forever Fertile.
Once the poop is in there, the only way to get ahead of the curve is to bind up the excess P. Aluminum sulfate/hydrated lime mixture, Phosloc, etc. all will do the same thing moving forward. BUT if you can't keep the geese off of there it will be an annual issue.
Last edited by Bill Cody; 07/07/2308:49 PM. Reason: Nutrient addition info
I have read about flashing lights you can use to discourage geese from visiting the pond in the winter months, but am afraid that those lights might be a problem for neighbors having to look at them constantly. Any thoughts on alternatives ?
After spraying Mizzen and a drop in the temp (85-88 instead of 95-102) the past 3 weeks, things have greatly improved and I have no floating mats at this time.
I recently moved into a property that has a pond with algae problems. We also had at some points over this past winter 2-3 dozen geese around the pond. We'd let me dog out, try to chase them away, but they'd just fly to the other side. We tried everything, the one thing that worked to get them to move on was a green laser pointer. Works miracles. Whenever the geese land on the property we just go outside and shine the laser around them and they immediately get agitated and fly off. I'm not concerned about their well being, there's literally dozens of large ponds in my town and they can find somewhere else to hang out.
You have to be careful though, we don't have neighbors in our sightline. Shining a laser pointer accidently into someones eyes is very dangerous.