Regarding Red Root Floaters do they need to be in an uncovered tank only?

[ScionTommy]

I wanted to ask because most of the information I found online suggests that red root floaters need to be in open tank is possible to keep them in a covered tank. Or the condensation from the lid would drip on the leaves causing them to rot?

[TOtrees]

In general, most floaters like calm still water with lots of light. If you have an airstone or sponge filter, then the bubbles popping at the surface will constantly wet the upper surface of the floater leaves, sometimes even quite far from where the bubbles come up. A closed lid will prevent the leaves from drying, and yes that (usually) leads to poor performance, ie reduced growth rate. But if the lid is open in the same scenario, and the tops can dry as fast or faster than they get wetted, and they'll be fine. 

FWIW I don't think that the harm from the leaves being wet is rot as much as it is reduced growth. Floating plants thrive so well in our tanks because unlike plants that are submerged, they have access to nearly unlimited CO2. If the leaves are wet (or sunken) that's no longer the case. Growth is then reduced. Plant success is all about growth exceeding loss. Wet leaves -> reduced growth -> losses (dieback) exceeding gains -> losing plants. 

IME duckweeds are the only floaters that do ok with wet leaves and anything more than a trickle of surface movement. Anything else (rr floaters, dwarf lettuce, salvinia, etc) needs a refuge if it's in a tank with surface movement, and also needs enough circulation/air movement over the leaves if there is bubbles. FYI all the same arguments (correction: opinions) about surface movement also apply to sub-surface circulation. None of the long-rooted surface plants will appreciate flow in the water column that tosses the roots around. Still water is best for them. 

Interestingly, it is possible with a large enough tank (or the right setup on a smaller one) to have some surface flow, and have the floating plants themselves become the barrier. Eg if the bubbles/flow are at the left side of the tank, you can get a good group/colony/mat of floaters going at the right. The plants furthest from the moving water will do best, and those at the edge of the open water will have the most difficulty, and may even be constantly replaced by progeny or shoots from the healthier ones. This can work with directional flow (eg water is lifted up at left, travels across top to right, and drops down at right and circulates back along bottom), but not so much with circular flow (which is less likely to allow plants to settle at one side). I have this working for me with rrf in a 10 gallon tank, with a lightly bubbling sponge filter, and a lid (open maybe 25% of the time). The rrf isn't going bananas, but it's holding steady. 

[ScionTommy]

Water flow shouldn't be an issue since I have tiger lotus that send up floating leaves are staying in place, due to a bit of java moss to buffering the water flowing out from my filters.  So, in my case most of the healthy plants would be in the front of the tank since I got air stones set up in the back, anyways thanks for the advice. 

[Odd Duck]

All of my red root floaters have been grown in covered tanks.  Most in tightly covered tanks and all with sponge filters.  They generally don’t prefer too much spatter or dripping on their leaves, but mostly they don’t like swirling on the surface.  If you can limit surface agitation, and have appropriate nutrition and light, they usually do OK despite the surface moisture.  The only time I’ve had a significant die off was when I let the plants get so piled up on each other that they started rotting/molding.  They were spilling over the sides of the tank (that tank had a gap) and the center plants started rotting.  I wish I had taken pics of them spilling over the sides.  This pic is a different tank with a fairly tightly closed lid.

 

There’s a sponge filter directly under the left side of these plants.  The bubbles pop under the leaves.

The lighter color leaves are where the black lid hinge blocks the light.

[Patrick_G]

I’ve found the humidity associated with a tight fitting lid helps red root floater or other floater grow, but they don’t like too much dripping.