As this is muddy water you may want to get a cheap sump pump or something semi-disposable or at least repairable in case you pick up a lot of dirt or small pebbles. Lining the pond as you go with a cheap tarp may keep the water cleaner and the bottom dirt drier. How about a tent? Carport-sized tents are 10 by 20 feet and may cover it all over. ThatÂs an easy answer for me as we have two, one up (and decorated thanks to my wife) and one we just use for parties, think they were in the $150 range. Check Pep Boys, Costco, ect.

Back years ago, I think in this forum, several members were interested in building vacuums specific to cleaning fish ponds. I was one who got into it. I developed several vacuums and went to several people's ponds to test vacuums in different conditions. Here's my page on vacuums. There's also links to building vacuums. I don't know your pond, but in general, some species of string algae when alive and mature is like horse hair. Bind a little together and it's like rope. I've pulled every bit of out of a pond in one pull and it brought pretty much everything in the pond with it up to the size of a brick. I don't think it would be possible to remove the string algae without removing the hornwort too. Once removed you could try and get some hornwort out of the string algae and replant. But string algae can come back, although often it's another species or it doesn't grow the same way next time. Even if you had no hornwort, gravel or reeds, I don't know of a single vacuum that is effective with string algae. If the string algae is still alive it is basically one plant and in your size pond when removed it could be in the 100-200 pound range. No vacuum can't handle that. I've seen a vacuum with a cutter on the end that's suppose to be able to cut the string algae. I doubt it works, but you should read reviews if considered. Even dead string algae, which breaks up easily is a big problem for a vacuum because of the volume. Easier to remove by hand or a swimming pool leaf rake. For live string algae I used 2 pieces of 1"x1" wood nailed or bolted together in the middle so they would open and close like scissors. I'd make them about 5' long. Open them a bit, push into the algae, close, and then spin them so the algae wrapped around the wood. Once I had a good ball I'd pull it out. Generally every bit of algae came along with this ball, along with anything it was attached to. Different species of string algae and the different life cycle stages can require different methods. I learned 2 basic things. First, there is no single vacuum that is effective. Ponds are cleaned in steps, removing big stuff first and ending with the small stuff. Different tools for each. Second, don't build a pond that's hard to clean. Loose rock, gravel, plants, all good great...until it's time to clean. I mortared rock so it was easy to clean and moved all plants into their own beds and so their crowns were above the water. Crowns above the water = no string algae = happy pond keeper. That means no underwater plants like hornwort and no lilies. Lilies can get their own pond or their own deep water bed adjacent to the pond so the pads can grow out over the fish pond.

Drain the pond of water that can saturate the plants, leave the plant mass to drain as far as is practical. Salvage pieces of plants that you like, snipping well rooted and shooted young hardy rhisomes for re planting When the plant mass is really dried it will weigh considerably less and yank out in large manageable chunks. Getting a rope round large sturdy clumps like iris and towing them out with a riding mower, or vehicle would save some lifting, using planks as a ramp to drag the mass up and out of the pond I'd estimate the lifting weight of dried pond plants can be a lot less than 20% of a wet mass, assuming there is a large volume of dirt and sediment accumulated that the plants have grown among

The Pathos will thrive completely under water or with leaves hanging over as lycopus describes. Under good conditions it may need some trimming every few months. An aside perhaps, it apparently won't take outside light levels so it won't thrive in shallow ponds outside in bright sunlight.