# Proportion of surface covered by floating plants



## HomeroThompson (Mar 15, 2020)

I've been wondering if anyone had any information regarding the appropriate level of covering by floating plants in a filterless set up. For example, I currently have two 10G whose entire surface is completely covered by frogbit, aside from some small "windows" I made with airline tubing. I've considered removing some of it and enlarging the "windows" to create bigger areas which are cordoned off. My desire to do this comes from the frogbit blocking quite a bit of light, plus they grow very large roots very quickly (which looks rather ugly), so that makes maintenance a bit more painful. Not trimming the roots isn't really an option, because they'll get to the subtrate and eventually make a mess. 

That being said, I'm worried about not having enough plants to keep up with the waste of the tank inhabitants (although both tanks are lightly stocked). Moreover, algae outcompeting my submersed plants is also a concern.


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## dwalstad (Apr 14, 2006)

I routinely remove floating plants so that submerged plants can get the light that they need. Plant pruning is essential for nutrient removal in an NPT. Otherwise, nutrients just build up.

A tank picture would help to show us what is going on. Every tank is different!


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## HomeroThompson (Mar 15, 2020)

Of course, here are some front and top pictures of both tanks


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## hoppycalif (Apr 7, 2005)

You are using floating rings to keep the floating plants out of some areas. I find it works better for me to use floating rings to keep the floating plants inside, and keep the rest of the water surface clear of floaters. I'm using Salvinia for my foaters. They don't grow the really long roots, and seem easier to control than frogbit. There are other choices in floaters too.


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## Michael (Jul 20, 2010)

Just a note, in some states all species of _Salvinia_ are prohibited as invasive aquatic plants.


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## HomeroThompson (Mar 15, 2020)

hoppycalif said:


> You are using floating rings to keep the floating plants out of some areas. I find it works better for me to use floating rings to keep the floating plants inside, and keep the rest of the water surface clear of floaters. I'm using Salvinia for my foaters. They don't grow the really long roots, and seem easier to control than frogbit. There are other choices in floaters too.


Thanks for your help.

I assume you find them to be able to keep up with the nitrates? How large are the rings, approximately?

I've never given Salvinia a try, I guess I could. I have some (very few) red root floaters that I'm trying to propagate (they're currently in a smaller jar), but my understanding is that they can be a bit more finicky.



Michael said:


> Just a note, in some states all species of _Salvinia_ are prohibited as invasive aquatic plants.


Thanks for the tip. They seem to be legal in Pennsylvania, unless I'm looking in the wrong place.


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## hoppycalif (Apr 7, 2005)

HomeroThompson said:


> Thanks for your help.
> 
> I assume you find them to be able to keep up with the nitrates? How large are the rings, approximately?
> 
> ...


I found that they can reproduce very, very fast. A hand full would cover the whole water surface in less than a week, so they obviously are using a lot of the nitrates, etc. Now that my rooted plants are growing better they don't reproduce as fast. I now have about 20% of the surface area inside the ring, and they keep it filled so I remove about a third of them every week. I haven't tried to find the optimum area.


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## dwalstad (Apr 14, 2006)

HomeroThompson said:


> I've been wondering if anyone had any information regarding the appropriate level of covering by floating plants in a filterless set up.
> 
> That being said, I'm worried about not having enough plants to keep up with the waste of the tank inhabitants (although both tanks are lightly stocked). Moreover, algae outcompeting my submersed plants is also a concern.


Nice tank! And good pictures. I would remove half of the Frogbit once it covers the surface. That way, your submerged plants can get some light, but the Frogbit colony is still there to do its job of removing nutrients efficiently.

Every day, I wrestle with how many floating plants I should remove from my 8 tanks.


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## hoppycalif (Apr 7, 2005)

dwalstad said:


> Every day, I wrestle with how many floating plants I should remove from my 8 tanks.


If it will help, I think I can find my old slide rule and loan it to you.


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## Karen in San Jose (Jun 1, 2020)

I love the look of the long roots of frogsbit. I don't think it's legal in CA, though. I am a complete newbie and I put red root floaters into my tank right off the bat and they are happily growing as the tank cycles. I don't find them to be finicky at all. The snails love them and so does my shrimp. I even found blackworms in them this morning. Nobody is eating them, just cleaning them and enjoying all the bacteria in them. The snails will wrestle one down to the substrate once in a while. If you find them on the substrate randomly, blame your snails.


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## HomeroThompson (Mar 15, 2020)

Thank you all! I'll be a tad more aggressive with my frogbit removal. Should I be unable to get good numbers of red root floaters, I'll try some salvinia.


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## tiger15 (Apr 9, 2017)

I used to keep an open area with a floating ring in my shrimp bowl for fear of cutting off air exchange. I gave it up after a while and the surface is now 100% covered with floaters. My shrimp are doing fine with no sign of oxygen deficiency.


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## dwalstad (Apr 14, 2006)

Your bowl must be well balanced. My bet is that the submerged plants in it are producing enough oxygen for the shrimp.


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## tiger15 (Apr 9, 2017)

dwalstad said:


> Your bowl must be well balanced. My bet is that the submerged plants in it are producing enough oxygen for the shrimp.


The reason I can get away with no opening on the surface is that the bioload is minuscule as I only have shrimp and snails in it. I don't think it will necessarily work if I have fish and heavier feeding.

The bowls have been set up for 2+ years with fully carpeted plants and floaters, zero tech, but strong sunlight from the window. Do floater roots give or take O2 during sunlight period.


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## tiger15 (Apr 9, 2017)

See pictures


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## Karen in San Jose (Jun 1, 2020)

HomeroThompson said:


> Thank you all! I'll be a tad more aggressive with my frogbit removal. Should I be unable to get good numbers of red root floaters, I'll try some salvinia.


I bought mine on Etsy - 30 of them for a really good price and very generous portions.


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## dwalstad (Apr 14, 2006)

tiger15 said:


> Do floater roots give or take O2 during sunlight period.


Like all plants, floaters give off oxygen with light. Most generated O2 probably goes into the air, but some O2 leaches down for required root respiration. Leftover O2 also leaks out from the roots, but most of that is typically taken up by attached bacteria. I don't think floaters are considered effective water oxygenators.

Even if the floaters cover the water, there's usually a crack or two in water surface where oxygen can get through. It's when floaters start dying that you could get major oxygen depletion. Bacterial decomposition of dead plant tissue will pull all remaining oxygen out of the water.


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