Check out my duckweed removal video.



With the $200 2" trash pump I have about $80 in to it.

Works like a charm!!!!

O.K., I'll bite. How does it separate the duckweed from the water?

It is not shown in the video because i added it afterwards, but I have three bulkheads on different sides and at different levels in the barrel. Connected to the bulkheads are three pool filters.
I get clean water out of the bulkheads, but three can only keep up if the trash pump is running at idle.
I also can run it faster with the discharge hose shooting into some brush on the bank of my pond and it seems to leave the duckweed (and watermeal) on the bank and let the water run back into the pond.

need more video!

I will video more of my setup as soon as i can.

How about pumping it over a frame with screen stretched over it let the water go down into the frame and then then your pool filters. You could sweep the material off the screen as it builds up

Replace the barrel with this - Dewaterer

The pump combined with the dewatering bag might also work great for my Aphizomenon bloom! I could suspend the dewatering bag from tractor forks over water and pump away. I wonder how long you could go before having to dump the bag and how difficult it would be get the bag cleaned out and ready to go. Any calculations on how long it would take a 2" trash pump to circulate one acre foot of water?

I also read 1 pound of phosphorus equates to 500lbs of vegetation. I am assuming that is dry weight of vegetation. I wonder how long it would take to remove 500lb of green stuff with this method.

32.6 hours to move 1 acre of water, 1 foot deep. 326,000 gallons and 2 inch trash pump pumps 10,000 gallons per hour.
But realistically it would be much less, because you’re only skimming the surface of the acre.

They make bigger dewatering bags, that is what is used when demucking a pond. I have no idea how to clean them out, I've seen them left in place for 6 months to a year, then cut apart and heavy equipment used to move the dried muck.

https://spillcontainment.com/products/ultra-dewatering-bags-oil-sediment-model/

Just do a google search for dewatering bags. That was the first place that popped up that wasn't an ad.

That was a good thought to use one to remove the algae in the pond. You might have to up the water flow to a 4" pump. You will have a LOT of water to move and circulate. I've dewatered ponds to lower the water volume when killing a pond, or getting it ready to renovate. I think for removing algae, it might be more beneficial to have the pump as far away from the dewatering bag as possible, so you aren't sucking up the cleaned water.

Curt - sorry to hijack, but I am loving the possibility!

Scott I REALLY like the idea of removing the algae. I could just have the intake and out let on opposite sides of my peninsula. I guess the dewatering bags are cheap enough I could just buy a few of them incase reusing them was not feasible. I know there is no way of knowing, but it sure would be interesting to know how many pounds of algae a big bag could when "maxed out". Apparently they sell Aphizomenon extract as some kind of supplement lol........

Journeyman - the part that is a more difficult for me is the grass blade bloom is throughout the water column. Would take much more time than just duckweed on the surface. Here's a pic.

One nice thing about a large dewatering bag, you can put a remote tank on the dewatering pump and walk away once you are sure it will run without babysitting it.

I dewatered a 1 ac 8' deep pond in a week by letting the pump run 24/7. 6 gallons would last roughly 24 hours. That was with a 3" pump upsizing to 4" belled end sanitation or sewer pipe and I was shoving the water 200 feet so it wouldn't run back into the pond. There was a 20' piece of 3" roll flat hose between the 4" hard pipe and the pump. It was a groundwater pond so there was water continually coming in that I had to overcome.

Scott do you have any pics of how you did the remote tank?

Just a cheap and easy option, but I've used construction site erosion fencing several times, and it's worked extremely well. I just run the pump outlet hose 20-30' from the bank on a gentle slope, and I've had nothing but clean water re-enter the pond. The algae and chopped up coontail never made it past the fencing. Portable and cheap.

Something like this

No but I can describe it easily. I took an older outboard motor gas tank that was metal. Flushed it out really well to get any traces of gasoline out of it and then let it sit for a week open inside a building so it would dry and any gas residue would be gone. Drilled a small hole near the bottom on the one vertical side, soldered a 1/4" pipe fitting to the tank, then a shutoff valve, then a barbed fitting that was the same size as the fuel line. Drained the fuel from the onboard pump tank. Disconnected the fuel line from the onboard tank at the carb, set the outboard motor tank on an upside down bucket so the tank bottom was the same height as the bottom of the "on board" tank. Ran new fuel line from the aux tank to the carb and everything worked fine.

I tried using a new plastic outboard tank that has the pickup from the top of the tank but there must have been a teeny, tiny air leak somewhere because it would run fine for an hour or two, but it wouldn't run all night, so I surmised that the pump motor sipped gas so slowly that it couldn't overcome the air leak and it built up enough to break the siphon.

I used a tank like this:
Outboard motor tank

Here are some more pics of my setup.

A 5 gallon bucket with a 2" bulkhead on the bottom of the bucket. this is connected to 2" PVC ending in a CamLock, which connects to the input hose going to the 2" trash pump.

On the output size of the trash pump, another CamLock (for easy connect/disconnect) going to 2" PVC in an upside down U, discharging into a 55 gallon drum.

I now have a cloth sack cylinder (home made with flour sack scraps sewn together) lining the 55 gallon drum to filter the duckweed and watermeal from the water. Several holes go around the sides of the barrel at the bottom to allow the water to filter/drain out. Chicken wire around the barrel keeps the filter cloth cylinder from pushing out of the barrel.

Oh sorry, forgot to add that the actual floating skimmer piece is an Admiral B38 floating weir skimmer, and the black piece on top of the bucket (that holds the skimmer in the center) is a 6" Hydroponics mesh bucket lid with the mesh cut off. You might be able to ust a regular bucket lid but i wanted something more firm.

I hope this helps someone.

One could probably also just hook the PVC pipes up to this....

https://www.123ponds.com/ap750b.htm...-4zzkhDbQNE6OJoNPuugdJw3JsxoC77IQAvD_BwE

I took Journeyman's advice and bought a dewatering bag. Works GREAT!!!!

https://youtube.com/shorts/-QpmxITpN1M?feature=share

I'm now testing a larger homemade skimmer combined with a floating housing so I can take the skimmer to the duckweed. the wind has to blow the duckweed a certain way for it to work when mounted on my dock.
I'll post results and plans for the skimmer if it works better than the 6" skimmer I'm using now.

Good to hear, thanks for reporting back!

Well we are almost a year out from the creation of my duckweed and watermeal removal system and there is not one trace of duckweed or watermeal in my pond. I also noticed that I haven't seen any coontail all year.
Did I remove all the nutrients? Did I mess up? I'm scared I overdid it.

Sounds like you did a great job.

I think the Year 2 results will determine if you "overdid" it.

I am not a pond plant expert, but I am pretty sure from my Pond Boss education that it is much easier to fertilize if you are short of nutrients, than it is to do all of the hard work to get excess nutrients out of the pond.

+ 1 on easier to add than subtract.

I'd love to see them!

+1 - I also can't picture what you describe at all. I would think your design could be modified with different size inlet/outlet and screening meshes and could possibly help remove floating FA as well. Please share when you can.