Hi all,
Floaters are not always the perfect solution, the problem being they can cut the light for the other plants below.
That is the idea really, they aren't CO2 limited, so you can use them to reduce light intensity to the submerged plants.
You have to have a balance between light intercepted and light transmitted (which probably only comes with experience for any particular aquarium/light/filter combination). Have a look at <"
Windowsill Nature">.
I do have some floating plants....... The last ones I had started to turn yellow so I removed them.
Now that is really useful, because it tells you straight away you are deficient in at least one nutrient.
It has to be nutrients because:
- your floating plants have access to 400ppm CO2
- and they are receiving plenty of light (PAR).
If nutrients weren't limiting then the plants would be "leaf" green, even in high light intensity. This is some growing, as an invasive alien, in a Californian irrigation channel where I would guess it is receiving a lot nutrients as well as a lot of light.
View attachment 99928
I've had some Frogbit in high light (they are in the glasshouse) with moderate nutrients and very active aeration, they grew very well for a while, but are now showing signs of iron deficiency. I'm pretty sure it is iron deficiency, because it is effecting the new leaf, and iron deficiency both causes chlorosis and is immobile within the plant (it can't be moved from older to younger leaves).
I've never had this happen before, using this growing system (they are for some experimental work) but I've never had such vigorous aeration before, and I assume the difference is that all the iron has oxidised.
It is the top plant in the image below.
View attachment 85536
The bottom plant is one that has been grown in high light (it is on a S. facing windowsill), but has been nutrient deprived.
You can't see quite so well, but it is the older leaves that are yellow. The nutrient deficiency that has caused yellowing is almost certainly either nitrogen (N) or potassium (K), both of which are required in large amounts by the plant, and are mobile within it, allowing the plant to export these nutrients from the older leaves to the newer leaves.
If I added the appropriate nutrient, then I would see a different response. In the case of the mobile elements (bottom plant) I would get a pretty instant greening.
In the top plant the old leaves would remain chlorotic, but the new leaves would be green.
cheers Darrel