Help needed: Algae in semi-natural stream and pond

[Tigger]

Let's see if I can keep a long story short:

Sump pump running almost constantly this time of year, feeding probably 2 gal/min of spring water into a long, narrow drainage ditch that empties into a small naturally-formed (more or less) pond. I dug the ditch/trench, and use some diverting rocks to create a constantly moist bed (where, for example, the 'Black Gamecock' LA Iris I got from Chris is having a field day). The pond was a natural depression, but I have dug it out some so it's about 18" deep at its deepest. The bottom is silty, with hard clay underneath that. The far end of the pond overflows into a drain that runs underground and out into the woods, where I've probably created one heck of a mosquito breeding ground, but what else could I do with the water? It does eventually run into a real creek.

This spring, however, the trench (and hence, the pond) have a LOT of that stringy green algae. The pond plants (water lilies and some other submersibles) are hairy with it. I could take a shovel along the whole length of the trench to try to cut it out, but that wouldn't be a lot of fun. I put a single "pond block" thingy at the top of the trench, but it didn't seem to make a dent.

The pond does have some potentially sacrificial fish, and lots of tadpoles and frogs, but (as I said) the outflow runs into the woods so I wouldn't want to use anything too toxic. I spent some time this spring laying rocks in and around the edge of the pond, and I really like how the water is flowing now, but I'm sick of cleaning out this goop.

For the record, I can turn the sump pump off for 2-3 hours before the basement starts to flood. (That's a separate story.) In case I need to let the trench dry out a little bit. And it should get dryer as the summer comes on.

Anyone have any advice? I could post a pic if that helps, but it's not much to look at right now other than the caltha palustris which is blooming so well right now.

David

[Tigger]

This picture isn't too bad. Water comes in at the upper right and flows out at the lower left.

I cleaned some of the gunk out after the pic was taken. The marsh marigold (caltha) is in a little "inlet" to the right, behind the peninsula of grasses. That's where the fish like to hide, although I've built some rock houses for them as well.

It's fun to play with, anyway.

[Gardentoad]

Since it has spring water feeding in, it will have a constant supply of minerals to grow algae.Otherwise I'd say to stop water changes so the minerals deplete somewhat.

Shade would help and competition from more higher forms of plants. You can acomplish both with plants that sit on the surface like water lilies, water hyacinth,water lettuce and many others.

Barly straw or dumping a bottle of peroxide(3%)will help. If you kill the algae you still have to remove it or algae will feed off of the decomposing plant matter.

You will probably have to do like I do and just put up with it. I bought a new toilet brush just for my pond and stream. It is pretty easy to just spin it around in the pond and pick up string algae like cotton candy on a stick. My stream only gets it real bad in the spring because it is well shaded after the trees leaf out. My little pond in full sun I had to clean it out much more often, every week or two. I have skimmers so I can't have free floating plants, but I do have water lilies.

My new ducks have eaten all the algae in it now but they also eat all my other plants in the water. I had to move all my water lilies out.

If you have frogs and toads that you want to multiply, leave the string algae in the spring. They both spawn in it. I just pull it from the filter and shallow, fast running parts of my stream right now.

[Tigger]

Thanks for the advice. A toilet brush sounds like a good idea, as I can use it to get the algae out of the trench.