# Yellowing frogbit: need to dose more?



## Jack B (3 Aug 2020)

I'm already dosing TNC Complete at double the recommended dose, daily - but my Amazon Frogbit persists with having a few yellow leaves. Can it really need more ferts, should I turn my attention elsewhere, or is this just normal?


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## Jack B (3 Aug 2020)

(My tank is low tech)


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## dw1305 (3 Aug 2020)

Hi all, 





Jack B said:


> but my Amazon Frogbit persists with having a few yellow leaves


That looks pretty healthy, just pinch off the old yellow leaves when you give it a thin. 

Because it is producing new leaves the older leaves will begin to lose their access to the light and the plant will withdraw the chlorophyll etc from them.

cheers Darrel


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## dw1305 (21 Sep 2020)

Hi all, 





Jack B said:


> but my Amazon Frogbit persists with having a few yellow leaves.


@Jack B , how is it looking now?

cheers Darrel


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## Jack B (14 Nov 2020)

dw1305 said:


> Hi all, @Jack B , how is it looking now?
> 
> cheers Darrel


@dw1305 sorry for the silence - turns out being a teacher is hectic right now!

And thanks for asking: it's not too bad - though there is quite a bit of yellow around - pic attached. I'm minded to swap back from TNC Lite to TNC complete, even if my water board report puts nitrate at 40ppm... If you have more thoughts I'd be happy to receive them

Best wishes
Jack


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## AverageWhiteBloke (14 Nov 2020)

They look a good size so maybe Nitrate isn't the issue. Are you adding any Magnesium? To be fair I would probably still go back to complete. The water report isn't cast in stone just an average of when they were testing. Over time with just partial water changes in a well planted tank it won't take long to burn off that nitrate.


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## Jack B (14 Nov 2020)

AverageWhiteBloke said:


> They look a good size so maybe Nitrate isn't the issue. Are you adding any Magnesium? To be fair I would probably still go back to complete. The water report isn't cast in stone just an average of when they were testing. Over time with just partial water changes in a well planted tank it won't take long to burn off that nitrate.


Thanks! When I get some time I plan to read up on EI and do it properly. In the meantime, no I'm not dosing Mg - might I need that on top of TNC? I'm a chemistry teacher so should be able to get some on the cheap  Is Epsom Salts the recommended form?


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## AverageWhiteBloke (15 Nov 2020)

Yes buddy epsom salts is the one. I've just had a quick look at the TNC stuff and there is the same amount of magnesium in both lite and complete albeit in small amounts. My understanding of using Duck weed to look for deficiency is new leaves would be iron, old leaves potassium and nitrate which the plants consume the most of. That just leaves magnesium which affects old leaves also. Potassium and Nitrate can also cause stunted growth in new and old leaves but yours look reasonably healthy. I would remove any poor foliage from under the leaves and have a shot with the magnesium, I think magnesium is mobile so you should see the leaves green back up if that's what you're lacking. @dw1305 is really the man for this one though, Duck weed index is his baby.

There is a law whose name escapes me right now, liebrig or something or other? It dictates that plants need all the trace elements plus N,P and K to form healthy plants if any of the above is missing it weakens the plant, look at it like building a wall without sand. That's why it is better to use a complete style fertiliser and ignore your water report. If there is some nitrate of phosphate coming out your tap then happy days you're belt and braces. Or you could save yourself a few quid and just buy the raw salts and mix it up yourself. Being a chemistry teacher you'll probably know better than most 

Regarding EI, Basically all those elements we mentioned earlier are put into the tank in amounts that the plants couldn't realistically use even under maximum growth and lighting. It is really for the high tech people who don't want to run out of ferts while they are pushing growth to its limits so they can concentrate on getting flow and co2 injection right. Us low tech users just need to make sure there's some of everything. That's where the Duck weed comes in handy, it's close to the light and doesn't get co2 issues as it gets it co2 from the atmosphere and not the water column which we all know is in abundance in the atmosphere  Duck weed reacts quicker to fert issues than the submerged plants so it's essentially a canary for the rest of the tank. 👍

Just to add, if it is nitogen you're lacking and there is a lot of nitrate in your tap water doing more or bigger water changes would help.


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## dw1305 (15 Nov 2020)

Hi all,


Jack B said:


> @dw1305 sorry for the silence - turns out being a teacher is hectic right now!


I bet, my wife is a teacher,  for the last couple of years she has been mainly working as a TA, but in 2020 a lot more time has been as a teacher and a lot less as a TA.


AverageWhiteBloke said:


> Yes buddy epsom salts is the one. I've just had a quick look at the TNC stuff and there is the same amount of magnesium in both lite and complete albeit in small amounts. My understanding of using Duck weed to look for deficiency is new leaves would be iron, old leaves potassium and nitrate which the plants consume the most of. That just leaves magnesium which effects old leaves also.


Try @AverageWhiteBloke 's suggestion, the plants look OK and a bit of extra Mg isn't going to do any harm. Your water won't contain much magnesium <"for geological reasons">, most of SE England has chalk aquifers, and chalk doesn't contribute much other than Ca++ and HCO3- ions.


Jack B said:


> I'm a chemistry teacher so should be able to get some on the cheap  Is Epsom Salts the recommended form?


Yes, "Epsom salts" (MgSO4.7H2O) and ~10% Mg.


AverageWhiteBloke said:


> There is a law whose name escapes me right now, liebrig or something or other? It dictates that plants need all the trace elements plus N,P and K to form healthy plants if any of the above is missing it weakens the plant, look at it like building a wall without sand.


<"Liebig's law of the minimum">.

cheers Darrel


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## Jack B (2 Jan 2021)

Well the Epsom Salts has been deployed for a month now and...I don't think it's fixed the issue. The Frogbit looks the same, and some stem plants (polysperma, H 53B) have holes in their leaves as per the attached pic. All the stem plants gradually lose lower leaves, though this seemed to be helped with root tabs.

It doesn't feel like an urgent situation since I don't mind picking out leaves at water change time, but obvs I'd like to get on top of this.

Which I guess brings me back to the Ferts Dosing section of the forum, which always makes me feel stupid for not being able to find/understand how to get started with DIY salts!

I think I need to know:

Which ions do plants need? Is it sufficient to only consider nitrate, phosphate, potassium, and then buy 'trace' ions together as @AverageWhiteBloke may be implying? Or do I need to buy a source of each ion, incl trace?
How do I choose the salts to buy? Do I work from my water report? I'm a chemistry teacher so should be able to cope with this (!) I guess both nitrate and phosphate come in combination with other useful (positive) metal ions, killing two birds with one stone
How do I choose how much to add of each salt to add (I think I just go off the forum's calculator?), and when? I've read some warnings about ions forming precipitates if added together: not sure how TNC complete avoids this.

If there's a post that covers these questions could someone please let me know? I'd like to master DIY salts for cost, interest, and plant health. Plus my TNC complete is about to run out again 

Cheers,
Jack
PS. here's a video of the tank in case that's anyone's cup of tea!


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## AverageWhiteBloke (2 Jan 2021)

Hiya mate, look in the articles section for dosing although this refers to estimate index which is maximum dosing but same applies. 
Dosing is spli into two types, macro dosing or your NPK and micro dosing all the trace elements. Plants feed on mainly the npk but they also require all the traces. 
A trace mix will contain the iron as well as obviously all the other trace elements. People mix and dose these separately because phosphate can react with iron when mixed together. You can get round this by making an all in one fert but you also need to add acid and potassium sorbate to the bottle to prevent the reaction. If I was you I stick for now of making the two separate bottle and dosing alternate days.


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## AverageWhiteBloke (2 Jan 2021)

Just to add to that mate. Phosphate is potassium phosphate po4 and nitrate is potassium nitrate kno3 so you do cover most of the potassium needs just by dosing these. But if you are dosing n and p light you might also need some extra potassium in the form of potassium sulphate. 

The recipe for making up the bottles is always roughly the same, how much you dose is up to you. If you want to be belt and braces you could dose ei levels to make sure you're not deficient in any thing then work your way backwards gradually decreasing the dose.


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## AverageWhiteBloke (2 Jan 2021)

Pull the yellow leaves off the duck weed and watch what happens with new growth. If the new growth is damaged (possibly through lack of iron) they probably won't repair anyway, my understanding is iron can't move to these new leaves. Magnesium should only green up the old leaves as it can move about in the plant. If you have upped the iron recently you need to see how this affects new growth going forward.


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## Jack B (11 Jan 2021)

Thanks @AverageWhiteBloke - have ordered APFUK starter kit and some high-ph-tolerant iron supplement too, having binged on X3NiTH's mega post within this thread. The new growth is pretty ropey so fingers crossed.

The adventure begins


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## Jack B (12 Feb 2021)

Frogbit greening up and other plants growing at record rates: thanks @AverageWhiteBloke and @dw1305. I'll play with levels when I have time, but for now it's problem solved. 

I've got some emersed S Repens that struggled in my tank last time I tried putting some in. Will have another go with EI conditions 🤞


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## AverageWhiteBloke (13 Feb 2021)

Jack B said:


> Frogbit greening up and other plants growing at record rates: thanks @AverageWhiteBloke and @dw1305.


Nice one mate, made my day to hear of a victory in the plant world. Don't expect any miracles with the S.Repens, I have some in my tank that are getting along fine, no visible growth to talk about in a non co2 tank but they are all healthy. I would expect it to take many months to see any noticeable spreading.


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## Jack B (17 Mar 2021)

Well @AverageWhiteBloke things definitely improved (indeed I was sure it was fixed!) but the Frogbit has settled into a state that is still a bit sickly....

This is with full EI dosing in a low tech setup, alternating micro macro six days per week after a big water change.

One thing that comes to mind: if my plants are failing to take up all the macros (inevitable, right?) then could they be precipitating out the micros like iron? I'm adding extra, but maybe not enough? Should l reduce the macros dose? Any thoughts gratefully received!!


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## AverageWhiteBloke (19 Mar 2021)

That's a tricky one mate, general rule of thumb is new leaves iron, old leaves magnesium and N and P affect both but tend to be old leaves first. My initial instinct there was magnesium which I'm assuming you are dosing in line with ei dosing? Growth looks good so considering EI nitrate probably isn't the issue. @dw1305 is really the man for this as he sort of pioneered the technique.


Jack B said:


> then could they be precipitating out the micros like iron?


Ferts reacting with each other and forcing plants not to be able to take up other nutrients isn't really my thing if I'm honest. I am aware of po4 reacting with iron but that's all I've got on that one. The only thing I could suggest would be rolling back a little on the fert dosing gradually. You seemed to have hit a sweet spot a while back then for some reason moved on to EI dosing which is totally unnecessary in a low tech tank IMO. In my tank which is densely planted, floaters and house plants with trailing routes going in to the water I dose a third of EI levels and change a third of the water weekly and haven't experienced any deficiency which would suggest I still have a little wiggle room on that.
Maybe the belt is conflicting with the braces when it comes to dosing? I'll see if I can find this thing I saved with which nutrients supposedly conflict with others which will no doubt let the genie out the bottle but I've always just stuck to the technique of providing just a little bit more than is needed at the same ratios as EI. I don't really have to take my tap water into account as most of the time I use rain water effectively starting with a blank canvas from a water POV.


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## dw1305 (19 Mar 2021)

Hi all,


AverageWhiteBloke said:


> @dw1305 is really the man for this as he sort of pioneered the technique.


I'm none the wiser either, there is definitely something not quite right, but I'm not sure what.

cheers Darrel


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## John q (19 Mar 2021)

Evening all,
I had a similar problem to this and I think in my case the culprit was light. The light in question was a fluval aquasky 2 and it sat about 30mm above the water, I suspect that it being so close to the frog bit caused it some issues.
I still have the light at the same height but I've reduced the output by about 25% over the last 4 weeks and the difference is quite remarkable.

This might not be the silver bullet jack and may well not be whats happening in your tank but I noticed you've recently raised your light height so it may well help.

Attached are pictures of an old leaf that was still attached to one of pods (don't know the technical term for a group of frog bit leaves) and a pod that represents the overall look of them now.

Oh and just for info Jack. My tank is also low tech and I dose about ⅕ ei dosing.


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