We dug a deep hole for our pond (about 3 foot deep at the deepest part) last summer. It stayed clean all season and we have a fountain actually two fountains running to keep the pond aerated. We have several frogs, fish, birds and crawfish that frequent and live in the pond. Lately the pond has been green. We have added the small hay bundles and pond algaecide to no avail. What information can I provide with my pictures to get help understanding how to clear the pond up without draining it? Or, do I need to do just that - drain the pond?

The long term cure is to deal with the excess nitrogen. Hay and barley straw bales are aimed at that, but a larger biological filter helps. Larger water plants compete directly with the algae as well. Regular small water changes can make a difference over time, but with a pond of any size could mean substantial water input.

The quick fix is a UV clarifier on your filter. This will kill the green water (suspended micro algae) outright and remove the green color, but there will be a die-off event that pulls oxygen from the water, and your nitrogen levels will actually go up, since the suspended algae is no longer removing it. Oxygenate heavily if you do this (bubblers, waterfall, etc.) and make sure your filter is rated for the size and fish load of your pond.

My pond is clear as a bell but it looks bad due to the growth on the bottom and sides. I do treat the pond with stuff to kill that algae off but with all sun and no shade it is about impossible to beat. I resign myself to the appearance 1) because the water itself is clear and 2) after all it is a pond not a swimming pool. And I see the fish eating the stuff. We do water changes, treatments, and vacuum a couple times each year taking huge amounts of algae out. Then the string algae starts up. I need to retreat as I saw it starting up in the little creek coming down from the biowell. But all in all I am happy and I suspect so are the fish.

I fought green water for years. The last few years I have solved the problem and I believe some of the reason for my good fortune is the addition of an UV light. It takes a while for it to work and needs to be run continually. It not only gets rid of suspended algae but helps with fish parasites. My fish would always get sick in the spring until I kept the UV going all winter.
I also stopped flushing and trying to clean my biological filter. I only disturb the filter once or twice a year buy flushing it with pond water. I scoop floating debris and try to keep my skimmers emptied too.
I also use a dry bacteria inoculant to keep the beneficial bacteria population high with every partial water change. I'll try and post a picture of the container.
My pond has a layer of what I call a 'bio-film' coating the inside. I never scrub it off. The fish nibble on it but I think it aids in keeping the beneficial biological activity that keep the pond balanced as much as possible.

I wonder if we are trying to keep out pond too clean. DH cleans the bio well at least two or three times a summer. It gets so gunked up with algae. Maybe the answer would be more bacteria. I use Aqua Meds brand and Microb-Lift. Also we scrub the gunk off the bottom and sides as best we can as it looks terrible. Not long but just yukky. But then I am not trying to cure green water. Mine is crystal clear, it is just that the sides and little creek from the biowell to the falls gets pretty gunked up if we don't keep on it. The skimmer has to be cleaned at least twice a day (probably could use more) as it gets clogged with the dead algae being sucked in by the pump.

Oberon46, I'm a bit curious about what you consider the yukky gunked up appearance is to you. Here is a picture of my pond/water garden. You can see the water is clear - see the shadows of the fish on the bottom? But the black liner is green now with a coating of algae. Is it the green color of the liner you don't like? Maybe you are talking about more of a string type algae?
The contraption on the bottom of the pond is now removed. That was unsightly but very functional. Its the pump and UV light attached to a repurposed plastic storage bin. I am going to replace the bulb and put it back into the pond in a less obvious place.
Do you have any pictures of your set up showing the stuff you think is unattractive? Thanks. Helen

I dislike the idea of having to use chemicals and contraptions to balance my pond water. I've found that shading the water from the sun by growing water lilies takes care of the majority of my algae problems. Like any other plant, algae needs sunlight to grow. The water lilies use up some nitrogen from the water as they grow out to cover, and they die back in the winter which allows the sun in to keep the water warm enough, and the algae hardly grows at all in winter. My water lilies are tropicals, but even hardy water lilies will do the job in cold winter areas, they start up growing as the water warms in spring, cover the water in summer when the algae would grow and die back at just the right time in the fall to keep things warm enough. Oh, and of course they help to cool the water in the summer, which is important here.

Some hungry, thirsty marginal plants like Cannas will also use up a lot of the nitrogen out of the water which will knock back the algae growth as well.

I also don't feed my fish at all, and they eat the algae, plus any errant insects, larvae and tadpoles in there as well. I have large healthy healthy fish. When I had fish that were dependent upon being fed, they would come up to the surface any time someone or something walked along the edge of the pond, so when the white heron came for a visit, they were lunch. No more feeding fish for me!

I agree with all of the above. We had a UV filter and it was great but now that it's dead the pond seems to be doing fine anyway. Summer of course is the hardest season for algae but if you put a good amount of plants in it will balance out. We also have a biological filter that we clean like once a year. I just spent two days pulling the overgrowth of plants out of my pond and the water underneath is crystal clear, and we have some huge koi in a small pond. The biological filter is just a half wine barrel (with liner) filled with lava rock that we pump the water through the bottom and exits out the top back into the pond. Then you add natural micro buggies that will live in the lava rock and eat algae and clean the water.

UV really works. If you have a heavy fish load it's almost a necessity. A large bio filter and 100wt UV keep my 20k pond clear to see 3ft down, makes easy work for the Heron's.

The top of my waterfall is a huge black tub and it is buried in the ground, and rocks placed around the edges. Inside the tub is water lettuce, hyacinths, and a papyrus to filter the water and I would say 90% of the time it does a great job. The few times it doesn't, really HOT and dry outside. I slit open a pillow and let the water from the waterfall run thru the fibers, once cleaned up, I pitch the pillow. Now it is not the most beautiful look while it is working but doesn't take long and works for me.

Or if you don't have an old pillow to sacrifice, you can get fiber cushion fillers at any fabric store for very little money. That's a great idea!

IMO all you need do is use more plants for greater surface coverage as Ursula mentioned above and have patience. If you have a waterfall and are in a hurry, the fiberfill is a good idea, bet you could find old pillows at the thrift stores.

Just make sure the pillows have not been washed with laundry detergent.

Huh. What an interesting idea. I have to fight string algae in the stream and around the edges of the pond. I use Algaway 5.4 which does a great job most of the time. I have full sun and a few plants in floating pots. Marsh poppies and water celery. Haven't tried to grow anything in the bio well as it is so full of bags of lava rock and three thick pads (3" thick) that I would be afraid it would just make DH's job of cleaning the well worse.

My two UV's (one 25 in a pressure filter and one stand alone 55W) may or may not be working. Well the 55 for sure isn't as I cannot get a tube up here. Have ordered two and both were broken. D is threatening to set up a daisy chained string of 3 25's and ditch the (very expensive) 55W. If anyone would like the body without the tube down where you can just go buy one and not ship it 3000 miles I would be happy to send for postage and $50. Cost over $200 without postage.

I will post pics today. Pond water is clear and fish happy.

Plants, plants and more plants. That was always the suggestion from my local pond store. Also, sometimes one needs to just wait it out - the pond needs to be balanced to be healthy. When I had a small open pond, it went through a couple unsightly algae blooms, but eventually sorted itself out. I didn't use any chemicals as this was the main water source for my dog and cats. If you live in the vicinity of dragonflies, I've read that they are a good sign of pond health. I chose that badge for my pond interest rather than the water lily. I now enjoy a pondless water feature, and still have dragonflies so I guess the water below the rocks must be in fairly good balance. When we first converted to pondless, I had chronic string algae on the rock columns (I just scrubbed it off), but now in its second year, not a problem.

Another thing I would occasionally do with my open pond was to add buckets of 'real' pond water from our creek-fed farm pond. I figured it had all sorts of growing things in it and the goldfish always went nuts when I poured in a bucket. Good luck!