Duckweed Index says Nitrogen please?

jameson_uk

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My Amazon Frogbit has been doing well for some time but is now looking a bit limp and yellowing.

The only ferts I have are Tropica Specialised Ferts which has NPK. I will dose a little of this now but in future are there some dry ferts I could add when they start looking like this?
dad12186cb152cccee11028dc11c34f4.jpg
 

hogan53

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You need to double the dose.....as your Frogbit are getting larger!
Or do more water changes!
Personally I would.... thin the older plants out to encourage new growth.
Snails will lay eggs under the leaves, new hatchlings will eat the underside!
Condensation onto the leaves will make them go brown on top!......Bottom left of picture;)
cheers
hoggie
 

jameson_uk

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Thinning was meant to happen this weekend but I was away so that is stored up for this weekend.

If it is nitrogen deficiency will more water changes actually help? This would reduce nitrates?
 

dw1305

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Hi all,
Tropica Specialised
Use a bit more, it should have everything in it, but it is an expensive option with lots of plants. Adding some "Epsom Salts" (MgSO4.7H2O) might be an idea, you can get them from a chemist etc.
If it is nitrogen deficiency
I don't think it is primarily, looking at the photo it definitely looks like the new leaves that are very pale and chlorotic, while some of the old leaves are "leaf green". Because it is the new leaves it is a deficiency of a non-motile element, and iron (Fe) is the most likely.

Because iron isn't mobile within the plant, when you add a plant available iron source it will only be the new leaves that green-up, and this will take a while.

If you have soft <"Elan Valley"> water you can use Fe EDTA as a chelator, if you have <"harder water"> then Fe DTPA or Fe EDDHA might be better.

cheers Darrel
 

jameson_uk

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If you have soft <"Elan Valley"> water you can use Fe EDTA as a chelator, if you have <"harder water"> then Fe DTPA or Fe EDDHA might be better.

cheers Darrel
Pretty hard water for me (KH=5 GH=12 and pH is ~7.8)

Perhaps I am being stupid or not searching for the right thing but where do you actually get Fe DTPA or EDDHA?

Looks like the Tropica ferts have HEEDTA ??? (http://www.theplantedtank.co.uk/traces.htm). The Flourish I do have lying around used Glucate which I think is the cheapest / least effective option in hard water?
 

dw1305

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Hi all,
HEEDTA ???
This is the best chelator for iron, but expensive, which is why I assume they use a small amount.

The iron may have come out of solution if you've had the "Tropica Specialised" for a while? Particularly if it has been stored in warm, light place.
The Flourish I do have lying around used Glucate which I think is the cheapest / least effective option in hard water?
The iron in gluconate is less strongly bound than in the chelated iron (Fe EDTA) etc. which means it goes out of solution more quickly in the tank, but you can try it, it won't do any harm.
but where do you actually get Fe DTPA or EDDHA?
Have a look at fertilisers for terrestrial plants. It isn't a product I've used, but <"Chempak Sequestered Iron"> contains Fe EDDHA, along with manganese (Mn) and magnesium (Mg). The Mg and Mn are included with the Fe because these three elements are the most likely options to cause chlorosis.

You can get Fe DTPA from <"Gardens Direct">, and there are plenty of sellers from <"continental Europe">.

I don't my plants very much, but when I do I use fertilisers like "Citrus liquid feed" etc. The reason for this is that they are <"cheap to buy remaindered at the end of the summer">, and they are fairly low in nitrogen, so you don't add much ammonia (nitrogen source in most terrestrial fertilsers will be ammonium nitrate (NH4NO3) or urea (CO(NH2)2)).

I don't recommend everyone does this, because there are obviously risks involved.

cheers Darrel
 

jameson_uk

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Thanks, really helpful as always
Hi all,This is the best chelator for iron, but expensive, which is why I assume they use a small amount.

The iron may have come out of solution if you've had the "Tropica Specialised" for a while? Particularly if it has been stored in warm, light place. The iron in gluconate is less strongly bound than in the chelated iron (Fe EDTA) etc. which means it goes out of solution more quickly in the tank, but you can try it, it won't do any harm.
The ferts have been sat in the cabinet under the tank. I bought it when I was trying to figure out a balance but gave up using it a while ago and everything settled down. I haven't dosed any in ages so I guess I need to start adding a little.

You mentioned Epsom salts. Is this because there might be a magnesium deficiency or am I missing the link?
 

dw1305

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Hi all,
You mentioned Epsom salts. Is this because there might be a magnesium deficiency or am I missing the link?
If you have hard (calcium rich) water it can interfere with the uptake of iron (Fe) and magnesium (Mg). There isn't <"much magnesium in most of the UK's water"> (unless you live in the Bromsgrove area?) and Epsom Salts are cheap to buy, so it may be worth adding some to improve the Ca:Mg ratio.

Magnesium deficiency is one of the causes of chlorosis, but magnesium is mobile in the plant (and so are nitrogen (N) & potassium (K)) and it effects older leaves first, so it isn't the primary cause of your Frogbit's yellow new leaves. When you are deficient in a mobile element you get pretty rapid greening, because the plant can move the element to the newest leaves, but with non-mobile elements it ca only incorporate the iron etc. in leaves as they grow.

When you add iron you may find you get a <"spurt of green algae growth">, because it can diffuse through the cell walls of the algae and trigger a fairly rapid response

cheers Darrel
 

jameson_uk

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Hi all,If you have hard (calcium rich) water it can interfere with the uptake of iron (Fe) and magnesium (Mg). There isn't <"much magnesium in most of the UK's water"> (unless you live in the Bromsgrove area?) and Epsom Salts are cheap to buy, so it may be worth adding some to improve the Ca:Mg ratio.
Makes sense. I live in Sutton Coldfield and I believe it is a ground water source with a lot of farm run off (I think they recently upgraded the water treatment works to reduce nitrates and they still average ~28 in their report). They do t however quote a figure for Mg.

When you add iron you may find you get a <"spurt of green algae growth">, because it can diffuse through the cell walls of the algae and trigger a fairly rapid response
The amanos, otos and nerites would be happy with some more algae!

I am away on holiday next week so I am going to do a 50% water change on Friday (and thin frogbit) then I will dose the Tropica Ferts and Flourish. Will see what it looks like when o get back...
 

dw1305

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Hi all,
I am colourblind which doesn't help and the wife is not around. To me this now looks more uniform???
It is definitely greener than the first photo, and the new leaves look a proper dark green.

What does it look like now?

cheers Darrel
 

jameson_uk

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Hi all, It is definitely greener than the first photo, and the new leaves look a proper dark green.

What does it look like now?

cheers Darrel
Away with work but will try and get another pic tomorrow. I removed quite a lot of the yellow leaves and any damaged ones.

It did appear to respond to the ferts which I guess means it was probably deficient in both mobile and non mobile elements. The Limnophila sessiliflora really seems to have picked up and new growth if far greener and bushier.

I am assuming the answer is trail and error but what sort of dosing regime should I try? None was obviously not enough but weekly was too much and I got lots of algae. Should I just wait until deficiencies are showing or try and preempt it? I added some ferts this time but it was just a case of putting a few squirts in rather than any sort of logic. Can you overdose micros? I am thinking that doing a full dose of Flourish after each weekly water change might be worthwhile (although the chelate isn't that great in hard water?)
 

dw1305

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Hi all,
It did appear to respond to the ferts which I guess means it was probably deficient in both mobile and non mobile elements.
Sounds likely.
Should I just wait until deficiencies are showing or try and preempt it?
I use the colour and growth of the Frogbit (via the Duckweed Index) to tell me when to feed, but I can see that might be difficult if you are red-green colour blind. You also have a bit of lag period for iron, in that it takes a while after you've spotted (and treated) a likely iron deficiency before new healthy leaves grow.
None was obviously not enough but weekly was too much and I got lots of algae
The algae can respond immediately to the addition of nutrients, because the ions diffuse through the cell wall, so there aren't any non-mobile elements for algae, they don't have (or need) any internal "plumbing".
I added some ferts this time but it was just a case of putting a few squirts in rather than any sort of logic. Can you overdose micros? I am thinking that doing a full dose of Flourish after each weekly water change might be worthwhile (although the chelate isn't that great in hard water?)
Give it a go, you can always play about with amounts "squirts" until you find a sweet spot. You are unlikely to overdose micros in hard water.
Got the wife to take a photo of how it is looking now.
dbd892d85c702ba95130609735f64f93.jpg
That is definitely looking a lot greener.

cheers Darrel
 
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