I thought I'd post a few of the things I am doing to control the floating plans we have in our tanks, mostly dwarf water lettuce, frogbit and salvinia minima.
Fish and shrimp love floating plants. But these things are super invasive and will cover the water surface blocking light to out precious rooted species causing lots of issues.
I have found and a few creative and inexpensive methods of controlling the roam of floaters, while culling them is the only way to control their volume.
"Suspension" Wire
I use the suction cups that come with the floating thermometers and tie fishing wire between them. Slight tension is needed, not much.
I positing the wire at the water line, or slightly below to accommodate evaporation, and about 4" from the front wall of the tank, so the floaters are contained in the fist 4" of the surface. You can do this at the front, back, sides or from all directions (both sides, front and back) to create any "window" through the floaters you want. All you need is the hardware.
Here's a diagram
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Here's a pic of the suction cup and some visible wire, hint: it's next to the airline
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Floating Ring
Four our tall round tank, I got tired of having to manage the floaters, removing them all the time, so I came up with this simple solution. I cut a length of standard airline tubing and made a circle using a straight-though fitting to close the tubing into a loop. I just let the ring float in the tank and put the floating plants in the margin between the tank walls and the ring. This leaves the middle open for light to pass through and for feeding.
For square and rectangular tanks you can use right angle fittings to form corners, or you can float multiple circles if you like... You can get the airline to "relax" and straighten out by training it in the sun over a few days, I haven't needed to deploy this solution yet but I am toying with it for my shrimp tanks right now.
Here's a pic of it filled in with leaves growing over the tubing, looks natural from the top and bottom as the roots and leaves obscure the view of the tubing.
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Our otos attach to the tubing sometimes, it's funny to see them just floating there, crazy sucker fish!
I'd love to see what others do and I'm open to feedback and recommendations; these are just two methods that work for me, but there always more to learn.
Enjoy!
NB about Salvinia minima, it's actually a member of the fern family and has a very cool leaf structure. This plant grows in ANY light, even in no light, and has a very pleasant color. I can survive in waters with salinity of 4-7ppt which makes an easy crossover to brackish and full blown marine setups. It can even survive being completely submerged for days/weeks as I often find a raft of it stuck below the leaves of other plants after the filter kicked it underwater. It has a larger relative, Salvinia molesta, and the genus Salvinia contains 10 species including Salvinia auriculata, Salvinia biloba, Salvinia herzogii, to name a few.
Close up of the fine hairs on S. minima leaves
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There are plenty of taxonometric and hobby sites out there that may say more about this plant as it applies to aquaria. Please note, this plant is considered invasive and a menace to commercial waterways, be careful with disposal of it and any plants you may no longer wish to keep.
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