1. How Can I Manually Remove Duckweed?

Sometimes, old-school works best. You grab a net, roll up your sleeves, and start scooping that stuff out. If the problem has not gone full invasion yet, this might do the trick.

• Step 1: Grab a fine net, or a good net set, and skim the surface. Go slow, though. Duckweed has this sneaky habit of sinking down when disturbed, only to pop right back up when you are not looking.
• Step 2: Missed a few bits? Use your hands to scoop out the stragglers. It is a bit tedious, but sometimes you have to get personal with these things.
• Step 3: Repeat. Duckweed is persistent, so you will probably have to do a few rounds.

Why it works: Duckweed floats, making it easy to scoop out. The catch? If you leave behind even a small piece, it can grow right back. So, this is more about maintenance than a one-time fix.

2. Can Machines Help Remove Duckweed?

Not in the mood for manual labor? Let the machines handle it. A surface skimmer could be your new best friend.

• Surface Skimmers: Devices like the Eheim Skim 350 sit on top of your tank, pulling in anything floating on the surface—duckweed included. Just set it up, and it does the work for you. You’ll still have to scoop the duckweed out as the filter draws it in. But it will do some of the leg work for you!
• Filter Adjustments: Another trick is adjusting your filter to pull from the surface, grabbing the duckweed before it has a chance to spread. Make sure it can handle the load without messing up your tank’s flow.

Why it works: These machines do not need breaks, so they keep working even when you are not. Ideal if your duckweed problem is big or if you just want to prevent it from becoming a bigger headache later.

3. Will Adding Fish, Shrimp, or Snails Remove Duckweed?

Letting nature handle your duckweed problem can be a nice, hands-off solution. Certain fish, shrimp, and snails are more than happy to munch on duckweed if given the chance.

• Herbivorous Fish: Goldfish and koi love to snack on duckweed. If you can house these guys, they will help mow down your problem. But, fair warning, they come with their own challenges—big fish, big waste, and they might snack on your other plants too. If you are thinking of keeping goldfish, check out my guide on goldfish care.
• Shrimp and Snails: Some shrimp and snails may help as well. They are not as aggressive about it as fish, but hey, every bit counts, right?

Why it works: Once these critters are in your tank, they handle things without any extra effort from you. Plus, there is something satisfying about watching them nibble away at the problem.

How Do I Keep Duckweed From Coming Back?

• Control the Light: Duckweed loves light, so keeping your tank out of direct sunlight is a must. If your tank sits near a window, try moving it or covering it up during the brightest parts of the day.
• Regular Maintenance: Stay on top of water changes and keep your tank clean. Duckweed thrives in nutrient-rich water, so keeping things tidy helps keep it at bay.
• Limit Nutrients: Duckweed feeds off of nitrates and phosphates. Use a good filter or just be careful with feeding, and you will keep the tank less inviting for that floating green mess. If you are unsure about nutrient levels, check out my post on managing high nitrates in aquariums.

Wrapping It Up

Duckweed can feel like an uphill battle, but with the right tools and a little patience, you can get ahead of it. Whether you go old-school and scoop it out, let a skimmer take over, or enlist the help of some hungry fish, you can definitely clear up your tank. Just stay on top of things once the duckweed is gone so it does not make a sneaky comeback.

Got your own tricks for duckweed control? Drop them in the comments—I love learning new things!