How do you safely remove seaweed from your pond?

Question

We have a large, hand dug pond (about football field size) that is about 7 years old. It is becoming very seaweedy. We have stocked the pond with large mouth bass....How can we kill the seaweed without killing the fish? We add crystal blue die every spring, but it's not really keeping on top of the problem anymore. Anyone know of any herbacides that are safe for fish and people? (as we do swim in it)

Answer 1

First off, I'm assuming it's algae, so what you need to do is provide more shade by either planting more Lilly pads. Increasing the overall depth of the pond as well as adding a current also reduces algae growth. Javel, or chlorine, when used in right concentration should be used as a last resort, given your pond seems to be self sustaining and natural.

Answer 2

Yes, the plants you don't want are filamentous algae. They grow on the bottom and eventually float to the top in mats. Raking them out by hand is the hard way to control the problem. Copper sulfate will work but you have to keep on using it through the summer.

If the pond does not run steadily to another body of water, you can get very sneaky and limit your problem  with a bag of fertilizer. Toward the end of winter, you place a bag of fertilizer on the ice, cut a big "X" in it and skid it out toward the spot over the deepest water. When the ice melts, you get the pond fertilized. Not what you want? Yes, it is. Early in the season, the filamentous algae have not gotten started yet and the nutrients are picked up by the unicellular algae. These shade the bottom of the pond and serve as the base of the food chain, up thru zooplankton, feeder fish, and the bass. Incidently, if those feeder fish are bluegilled sunfish, you have to fish them very heavily to keep the pond in balance. Forget about being sporting; net them out. Sunfish fillets smoke nicely and the ones that are too small to fillet make good fertilizer for the garden.

Answer 3

You have pestiferous aquatic vegetation, not seaweed. And definitely do NOT add additional vegetation therein, especially water hyacinth or lilly pads, since these simply add to the problem.  Depending upon the type of vegetation, responses you make can be very different.

Mechanical means is the best means of removal, but since these types of plants reproduce by regeneration of parts, any pieces that break off will grow new plants.  This is particulary true of a pondweed known as coontail, but also true of a species called stringy pond weed.

I live on a slough that was dammed off and deepened to hold water year 'round.  In mid summer, the coontail is growing by leaps and bounds.  Since I don't like to swim in this water, I remove the coontail by using a garden rake (no, not yard rake!) attached to a very long pipe. This process will wear you out, but if you and others take turns and stay on top of the matter (don't whimp out like most city-slicker yuppies do!), you can remove considerable amounts.  It is heavy but becomes feather light after a day in the sun.  Then, it can be used as garden mulch or piled into a compost pile.

Chemical treatment of ponds the size as yours is prohibitively expensive, but I'd recommend two that are used in this region of southeast Texas: Sonar and Karmex (spelling probbly not correct).  Sonar is great for the plants I've mentioned but expensive (like $400/pint, or maybe qt., and that is the amount and cost to treat an acre pond). The Karmex is a "pre-emergent" herbicide (used mostly hereabout by rice farmers, to kill aquatic plants as they emerge, so they do not become a problem during early stages of the rice growth). From the size you mention, I'd say you did not dig the entire pond, as one does a dirt pit, but that yours is an impounded stock pond, made by digging four canals or ditches and placing the earth on the sides away from the center of the pond, such that the center of the pond is ground that is at the same level as it always was.  These type reservoirs are easy to clean out by machinery but require being drained and then worked to till in the vegetation and then the pond refilled and start anew. Obviously this would kill out your fish, which I believe is something you don't want to do, so drain down to just the canals, treat them with Sonar and let the center, ground-level portion clean itself by the vegetation drying out.  You may need to treat it with some Karmex as it is very gradually refilled (best done by rain water, not by pumping water in (that is, if you choose to use the Karmex as it fills). This way, your fish will have been safe in the canal areas as the center dried out and cleaned itself.

E-mail me and tell me more.  I've dealt with this type stuff for twenty five years.

Answer 4

You need to put in some weed eating fish such as the carp. (These look like huge gold fish)You would need approximately two dozen. Chemicals will affect many things so be careful. Are you airating with a fountain or spray? If so this could also contibute to extra oxygen (good for fish bad for weeds)

Answer 5

what you have is not sea weed . i have a pond about half the size of yours stocked with trout . the weed i have is called parrot feather . here is a company you can call they are quite helpful. 1  800  328  9350. they sell different chemicals that you can put in your pond that wont harm fish. i chose not to  use the chemical instead i drug my pond with an old dump hay rake with my bob cat. and a long cable. you could use about anything that would grab hold of it.  it pulls out real easy, it dosent root real deep just about an inch or two at the most . i believe you have the same weed ido because it does look like sea weed by the way the name of the company is aquacide  company  1027 9 th street p. o. box10748   white bear lake mn.   55110  o748  hope this helps  good luck.