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What is the “Duckweed Index” all about?

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Dunno if it's been mentioned, but here's a side-by-side comparison between duckweed, Frogbit, RRFs and some Spirodela polyrhiza. Sort of an intermediate between the two, if you don't want to deal with the MASSIVE root systems I have on my Frogbits.
 
Salvinia does really well in my aquariums and l can sort of work out how much TNC Complete to dose after a while. Now far less than l initially used, just add at water change , all plants seem to be doing well
 
Hi all,
hypnogogia said:
Doesn't the root system get larger when there is a lack of nutrients for them?
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We think it probably does (via <"resource partition">). My plants tend to have relatively small leaf rosette, but long and bountiful roots, which I think is a response to fairly lean rations.

It is really the ratio of rosette to root that is important, <"if you have a very large plant it will have large roots">. These are @castle 's plants wher ethe roots had reached the substrate <"Looks like my Limnobium laevigatum has flowered?">

cheers Darrel
 
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Here’s two bits of RRF, both grown under the same light in the same tap water (soft) but the red one has been limited of nutrients. It has taken a long time for the plant to get that deep red colour and you’d probably see nutrient deficiency problems elsewhere before it became a useful indicator.

It is pretty though.

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dw1305 said:
Hi all,

We think it probably does (via <"resource partition">). My plants tend to have relatively small leaf rosette, but long and bountiful roots, which I think is a response to fairly lean rations.

It is really the ratio of rosette to root that is important, <"if you have a very large plant it will have large roots">. These are @castle 's plants wher ethe roots had reached the substrate <"Looks like my Limnobium laevigatum has flowered?">

cheers Darrel
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Castle's are absolute monsters. Mine are marginally fuller than yours, Darrel. When the roots reach the substrate it is a PITA too, when you pull them out they muck everything up...

I really like the polyrhizas. They get flak since they look likee lemnas, but they're larger and don't act as a bloody bioweapon so.
 
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I think you'd have to be careful with the RRF as light plays into the colour. I've had it growing packed densly (so much it didn't move) in a tank with the light about 1" above the surface and there was a very noticable line across the plant growth showing the extent of the light - red under the light and green around the edges. I've also taken them out of the tank, and floated them in tank water on the window sill and you get the deep red colouration. It a very cool plant but I think the light reaction adds an extra variable that wouldn't be helpful for the dcukweed index.

When it's happy it will grow over the top of itself and almost convert to emersed type branches where only the base sets of leaves touch the water and root with the offshoots growing up so it's packed an inch or more thick and out of the water supported by other plants below. On the other hand, if it's not happy it disintergrates readily.
 
tam said:
I think you'd have to be careful with the RRF as light plays into the colour. I've had it growing packed densly (so much it didn't move) in a tank with the light about 1" above the surface and there was a very noticable line across the plant growth showing the extent of the light - red under the light and green around the edges. I've also taken them out of the tank, and floated them in tank water on the window sill and you get the deep red colouration. It a very cool plant but I think the light reaction adds an extra variable that wouldn't be helpful for the dcukweed index.

When it's happy it will grow over the top of itself and almost convert to emersed type branches where only the base sets of leaves touch the water and root with the offshoots growing up so it's packed an inch or more thick and out of the water supported by other plants below. On the other hand, if it's not happy it disintergrates readily.
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This is interesting, I don’t know how significantly this will be a factor, however perhaps those plants under the light are not red directly due to the intense spectrum, but perhaps due to the lighting intensity driving the rate of growth? A very close to the surface light offers little surface spread, those under the light maybe simply trying to grow faster which turns their fertilisation from plenty (like those of the green outer shaded plants) to limited (red under direct strong light) simply due to the dictated rate of growth …the windowsill plants again maybe don’t get the same level of constant fertilisation as the tank so eventually turn red…..just a thought 🤷🏼‍♂️
 
tam said:
I think you'd have to be careful with the RRF as light plays into the colour.
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Ady34 said:
I don’t know how significantly this will be a factor
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Here’s some RRF I left in a bucket. The lighting is poor. The nutrients even more so. You can see the older growth still has a little green tint to it but the newer growth is more red. It’s the same across the bucket. It looks almost brown in this photo because the lighting is so terrible. 😄

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