Floating Pond Scum

[TomA]

I have a small 220gallon preformed pond in the backyard.

This year there seems to be an over abundance of some sort of algae.  It grows all over the walls, rocks and plants.  It seems to grow in strands of ¾ to 1 inch and then cuts loose to float on the surface. I believe it is Filamentous Algae - aka string algae.

Each day when I get back from work, half the surface area is covered.  So each day I skim off the surface.  Since I totally cleaned the pond this spring there are no decaying weeds or junk on the bottom to supply nutrients to support it's growth and I only have one Koi and 3 large gold fish living in it.  I do have a bird problem in that they line up to have their daily baths in the rock fountain.  The crackles (black birds) are the worst at leaving their droppings behind in the water.

Do you think it is due to the large amounts of spring rain and now hot temperatures that are bringing this about? I have no pond cover as of yet, the lilies seemed to be growing earlier but now they seem to have died off and the single water hyacinth has just now started propagating into three.

The water is clear and with exception of the string algae.

I have two pumps. One is a rock fountain and the other comes from the bio filter on the bottom of the pond.  I have directed its outtake towards the side of the pond to create a small current.  The bio filter has to cleaned ever three days due to the amount of algae it is capturing.

Does anyone else have this algae problem, how are your ponds?

[Fishnut]

It is likely a combination of too much nutrients and too much light.  Is there a way you can shelter your pond from the sunlight?  Try to get your hands on some duckweed.  It's great for covering the surface of the pond and effectively preventing the algae from growing a lot and the fish will be able to snack on it.  If you contact our newly elected President for next year's exec. he has some great large size duckweed that will do a great job.

Are you feeding your fish?  I bet they would munch on the algae as it's growing on the side of the pond if they had significantly less commercial food to eat.

I had a problem with the single cell algae in the spring for the same reason.  The pond is under our gazebo (the metal frame ones you see at Home Depot) so I put the cover on the Gazebo and the mesh around the edges.  That has significantly cut down on the light the pond gets and I used a UV sterilizer to combat the algae that was in there already.

[TomA]

Yeah, I'm thinking duckweed as well.  I was hoping that the water would balance out eventually as I am not adding any nutrients and not feeding the fish.  There is no way 4 fish is giving that much energy to the pond.  Plus I do not want to add any chemicals to kill the algae.

The goldfish spawned indoors over winter so maybe it is time to add some of those ones to the pond to assist in eating the stuff but there is no way they can munch it all down.  It looks like the roof of a cave if you turned it 180 degrees.

[The Pond Boy]

Or you can use Hydrogen Peroxide or another algae killer to kill the string algae. But I agree, the algae love the sun, no shade and the warm weather.
Thanks,

Greg Veldhuizen
The Pond Boy
www.thepondboy.com

[TomA]

Well I just got back from a trip and all the fish are dead.  Kids said there was a hot day and they found them all floating.   I suspect the oxygen levels must have dropped.

Sad.  The Koi survived winter only to die in the summer warmth.

[jpuncher]

Sorry to hear about your fish. It is hard to have them for so long, see them last through the winter and die when it has not been excessively hot.

I have had a pond for years - 500+ gallons. I had ponds in my yard when I lived in NC - pretty hot climate and in full sun with 18 inch Koi fish. I tried to plant as much on the shelves as that they would accommodate to eat up the excess nutrients in the water and starve any algae. What size pumps and what are their flows? I would look at getting a min 1,200 GPH pump with an external filter - Laguna has some good ones. To help with the algae, I would add a 16 watt UV sterilizer/clarifier (Tetra Greenfree UV clarifier is good) that can be attached to your external filter. You can also try some Pond Zyme or Biozyme an all natural clarifier - no chemicals and not harmful to your plants or fish). All natural barley straw pads can be thrown into the water as well.

As for the water and heat, you can buy some blue water coloring - Crystal Clear Pond Tint. The blue tint will make the water a little cooler for the inhabitants. Also, it would be good to have some surface disturbance. I would divert the second pump into a fountain head - water bell gives a nice touch. This breaks up the surface, oxygenates the water some and refracts some of the direct sunlight.

Hope this helps.