Gas exchange (when your tank is wall-to-wall with floating plants)

Hyoscine

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Hey, sorry if this has been asked before, but is it potentially problematic to have a complete coverage of floating plants? I've got good circulation in my small bedside tank, but practically zero water surface.

I'm hoping to hear it's fine as I really like how it looks, but I'll be adding some shrimp soon and I'm worried about oxygenation. Is there a minimum amount of surface area I should aim for? Could I mitigate the problem by adding a venturi? I'd really appreciate some advice, thanks.
 

ian_m

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If worried, use an air stone or put a floating ring (kids toy ?) on the surface to leave some water surface exposed.
 

Hyoscine

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Yeah, a floaty thing or just cordoning off a bit of tank is probably the way I'd go about clearing some space, but I just don't know if I need to.

With an air stone or a venturi, I understand that they work by disrupting the water surface more than injecting gas directly into the water column... Do you think there's any advantage to them in my situation?
 

Blightswine

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My understanding of venturi is that they draw atmospheric air in through the vacuum created by the flowing water. This can increase surface agitation but is dependent on the positioning of the outlet. In my experience, if the outlet itself is close enough to the surface, it makes the venturi relatively redundant.

As for an airstone, I imagine the surface agitation caused would result in pushing floaters away from the surface directly above it anyhow. Cordoning off a spot as Ian said is probably the cheapest/simplest option. I would simply make sure there's enough flow near the no-go-zone and you should be safe :)
 

dw1305

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Hi all,
Hey, sorry if this has been asked before, but is it potentially problematic to have a complete coverage of floating plants? I've got good circulation in my small bedside tank, but practically zero water surface.
Depends a little bit on the floater. Pistia is OK as a carpet, because the leaves don't lie flat on the water, but thick Lemna can inhibit oxygen exchange. Why don't you just remove 1/2 of it?

cheers Darrel
 

Hyoscine

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Why don't you just remove 1/2 of it?

Because it looks so coooool... :(

Yeah though, I've got a mix of frogbit and salvinia cucullata going on that must be at least as dense a coverage as thick lemna would be. Guess I should scoop out at least a little.

Thanks everyone!
 

dw1305

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Hi all,
Because it looks so coooool...
I always have some floating plants on all the tanks. I give my spare Frogbit etc to a local LFS, and he gives it away to people when he thinks their tanks need it.
As for an air-stone, I imagine the surface agitation caused would result in pushing floaters away from the surface directly above it anyhow.
I couldn't find it last night, but in <"Windowsill Nature"> "Akwascape" has done just this.

instashot_20150507_180214_zps54kxhtsg-jpg.6845.jpg


cheers Darrel
 
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