Floating plants and PAR

[Jake101]

Hi,

I have just redecorated my low-tech, and have only floating plants. These plants are categorised to have "medium" light needs, so I would like to have a some kind of an idea of a suitable PAR range on the surface.

Also, I am happy to hear any experiences of floating plants which adapt well to low humidity. It is an open-top tank and the humidity in our apartment is quite low especially during winters.

Thanks!

 

[zozo]

What floating plant are you refering to? Frogbit, salvinia natans, duckweed, hygrorhiza arista are pretty easy, since they float on the water surface no need to worry about humidity. H. arista is more dependend on ferts than light, S. natans addapts very good and stays very small in aquarium.. Have growing all doing ok without knowing any par values in 3 tanks, from low to medium light condition..

Pistia is a plant rather needing a sunny spot to realy thrive and could be difficult to keep in aquarium.

 

[Jake101]

Thanks, zozo. I am trying several plants atm. Pistia, Frogbit, Floating antlerfern (Ceratopteris pteridoides) and Azolla caroliniana.

 

[zozo]

Azolla caroliniana

There you have your par meter (sort of) give it 12 hours and if it turns red 🙂 your in the high light range.

 

[louis_last]

Pistia stratiotes dwarf and regular forms thrive in low humidity, they can actually struggle and begin to rot in closed top tanks where the humidity is too high. I have the dwarf variety in an open top tank under a wavepoint led strip light and it would cover the entire surface in a week if I didn't remove it constantly to feed the chickens.

 

[zozo]

Pistia stratiotes dwarf

Seems officinaly not to excist, it is the regular form and just a trade name.. Probaly the same as Salvinia natans does..

Grows like this with plenty of sun and ferts..


And in the aqaurium minus the plenty of sun it doesn't grow bigger than this.

 

[louis_last]

I think you are probably right zozo, the 'dwarf' variety can certainly unexpectedly begin to produce full sized plants although I've not had it happen to me. There seems to be a wide range of environmental triggers that can affect it's growth form.
Although my lighting has remained constant the pistia has shown three distinct growth patterns when other factors have changed. The tank had a really, really severe BGA infestation while I was away that smothered each and every plant apart from the pistia which had responded by growing huge, vigorous, trailing root systems that reached all the way through the water column down to the substrate - I don't know why and the new growth quickly reverted once the BGA was dealt with.
Its mode of reproduction also changes for me depending on how crowded it is, if the surface area available for the plants to colonize is restricted then pups just seem to split from the mother plant whereas if it's given more open surface to grow into it begins to grow stalks about 3" long and new plants form on the tips so I end up with a larger mother plant with several pups spread around it on spokes like a wheel.