My Pond Has Turned to Green Pea Soup

Questions for the pondlady:
I followed all the rules, did everything you said to do, Jan, but my pond is completely green. I couldn't buy all the submerged vegetation at once, so am buying it a little every week. Oh, and my grandkids feed the fish, but only when they come over.

PL answers: Add more underwater vegetation. Without enough the pond will turn green. The fish love to eat it and, the fish will eat it faster than it grows if you don't have enough. Without extra filtration, you must have 1 bunch of submerged vegetation per square foot of surface. If not, the fish will eat it all and you will be buying it every week forever. And it's a very expensive fish food.

And how often do your grandchildren come over?? And are they feeding those fish Poptarts? If those grandkids must feed the fish, chop up some cooked carrots, or green beans. And then feed them less than a teaspoon. This assumes the feeders visit only once weekly, not daily.

Excess fertilizer will turn the pond green. Stagger your fertilization schedule if necessary. Change 25% of your water weekly until pond clears.(Don't forget the dechlor.) Changing the water is important for the pond. And the veggie beds love it.

Plants and Fish

IF YOU HAVE KOI, DISREGARD THIS POST! Koi eat plants, all plants, all the time. You can screen off your koi or your plants, but if you allow the koi access to the plants, you will have larger koi and fewer plants.

For a garden pond to be successful, it must contain both plants and fish. Not only is this an optimum esthetic condition; but a balanced biotope with interactions between plants and fish will ensure proper water conditions, reduce insects, especially mosquitos, since the fish consume their larva, and plants will greatly reduce the development of algae.

Plants and fish benefit each other in two ways. First, fish and plants contribute to the successful functioning of the nitrogen cycle. As the waste products excreted by fish are released into the water, they are converted to ammonia and then to nitrites and nitrates by nitrifying bacteria. Nitrates are a food or fertilizer for plants and algae. As they are absorbed, plants and algae become a valuable food resource for fish, thus completing the nitrogen cycle.

This ongoing biological cycle ensures healthy pond life. It is important to realize that if plants are not thriving, algae will take over and the water will become murky.

A second important way fish and plants complement one other is through the process of photosynthesis. Fish require oxygen for their existence and they release carbon dioxide. Plants in turn require carbon dioxide for their successful existence and emit oxygen. During sunlight, plants will consume the carbon dioxide released by fish and in turn emit oxygen required by fish.

A constantly functioning nitrogen cycle and photosynthesis are the key components to a successful and beautiful garden pond. The most beautiful type of pond plants are lilies. Water lettuce and water hyacinths are also excellent additions to the pond and submerged plants such as Hornwort, Vallisneria, Sagitarria, Cabomba and Anacharis are also excellent. The ideal pond fish are common or hardy goldfish.

My pond looks like pea soup

An algae bloom is normal when the pond is brand new. If you are patient and the pond is properly balanced, you may not have one, but don't be dismayed if you do. If it lasts more than a week and you absolutely MUST be rid of it because your mother in law is coming to visit tomorrow, there is an emergency procedure you can do right this minute and your pond will be clear by tomorrow. This is not a permanent fixture in your pond, nor is it the universal panacea for algae, but it will get that pond clear so you can show off your brand new handiwork to your visitors.

Do not use any of the algaecides that are available commercially. Most of them severely decrease the oxygen level in the pond and that will kill the fish. Remember that anything that will kill algae will kill other plants. Fish will tolerate green water--they will not tolerate toxic (albeit clear) water. If you have consistently green water use more submerged vegetation (Anacharis) and make sure at least 50% of the water surface is covered with floating vegetation to provide shade. This floating vegetation can be water lilies, water hyacinths, water poppies, etc. And stop feeding those goldfish.

If you must get rid of your green water fast use a temporary mechanical filter. I use a large black pot that a plant has come in--10" or bigger I also put a few more holes in it than just the one on the bottom. Be sure the holes are on the bottom of the pot or whatever container you use. I put 2 inches of foam rubber in the bottom of the pot and suspend it over the surface of the water. I usually use a lawn chair or upturned 5 gallon bucket. Next I run the hose from the pump over the top of the pot so the water runs through the foam rubber. I hold it down with a brick. This makeshift filter looks awful and must be cleaned every 2 hours or so, but it will clear up your pond in a day or two for the cost of the foam rubber. You can tell when the foam rubber has to be taken out and cleaned because the water will start running over the top of the pot. The finer the foam, the more often you must clean it, but the faster your pond will get clear. You must keep an eye on this jerry-rigged set up and continue to clean the foam rubber or your pond will not clear up.