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I've written a proper Duckweed Index guide

dw1305

Well-Known Member
5 Year Member
Messages
2,783
Location
Wiltshire UK
Hi all,
I know there are some users of the <"Duckweed Index"> users on <"Apistogramma.com"> so I'll link in the Duckweed Index article I've written for the UKAPS forum.

<"https://www.ukaps.org/forum/threads/what-is-the-“duckweed-index”-all-about.73647">

Fundamentally, the “Duckweed Index” is a simple technique <”to retain and improve water quality”>

Quick guide.
  1. To use the “Duckweed Index”, you watch the leaf colour, and growth rate, of a floating plant, and you only<" add nutrients">* when plant leaf colour and / or growth decline.
  2. “Amazon Frogbit” is now my preferred “Duckweed”.
  3. You use the <"UC Leaf Colour Chart”> as your visual reference for plant colour : <” The scientific background to the "Leaf Colour Chart">
  4. Plants require all <"fourteen essential mineral nutrients"> to grow, just in widely varying amounts.
  5. You can use the combination of leaf colour and plant growth rate as a measure of plant nutrient availability.
  6. Using the “Duckweed Index” water testing is not a requirement and you don’t need to try and accurately diagnose any nutrient deficiencies.
  7. Synergistic plant / microbe biofiltration can both create, and retain, high water quality.
  8. Bioassay and phytoremediation techniques have a sound scientific underpinning.
  9. The “Duckweed” functions simultaneously as both the bioassay organism and your “test kit”.
  10. When you thin the plants, you remove the nutrients they contain from the aquarium.

cheers Darrel
 
Last edited:

anewbie

Well-Known Member
Messages
1,424
two comments:
How do you tell if 'growth rate' changes - that seems like the hard one.
Funny you should post this today; i just put in two very strong power-heads to kill my duckweed.
 

dw1305

Well-Known Member
5 Year Member
Messages
2,783
Location
Wiltshire UK
Hi all,
two comments:
How do you tell if 'growth rate' changes - that seems like the hard one.
It is actually reasonably easy, floating plants don't have much requirement for structural support, so they tend to just produce large spongy mesophyll cells which they can "tack" photosynthetic tissue to. Because they are never CO2 limited this means that they can produce a lot of new leaves really quickly.
Funny you should post this today; i just put in two very strong power-heads to kill my duckweed.
That is sort of your first point. It is the ability to spread that in response to nutrient levels that makes the Duckweeds (Lemna spp.), such a PITA, which was one reason that my preferred "Duckweed" is now Amazon Frogbit (Limnobium laevigatum).

cheers Darrel
 

MacZ

Well-Known Member
Messages
3,119
Location
Germany
Hi,

This thing should be attached to the front page somehow.
Use the report-function and ask for pinning the topic. That's what I did to get my medical template and the medlist-link pinned. Ideal would be if Darrell did this himself.

Also for my fellow german users: I've offered to do a german language translation. If anyone is interested to proofread or wants the finished translation, ask me in late January.
 

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