TNC Complete - EI equivalent dosing

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I have been unimpressed with the plant growth in my 20 litre tank since it was planted about 4 or 5 weeks ago. Plants seem to be surviving, but not thriving. My light is generous, and I have no significant algae.

Even supposedly "easy" stem plants like Hottonia palustris are not romping away as I would expect. The tissue culture of Rotala walichii has grown a lot, but the growth lacks the lush feathery quality that I would expect. The tips have gone a slight coppery colour, but not a rich pinky-purple. There are two plants doing well: the Eliocharis acicularis "mini", and the Amazon Frogbit which I added 4 or 5 days ago (the latter is growing at a rate that might begin to scare me).

I’m pretty sure my CO₂ is okay, and I have repositioned my spray bar to give good distribution - the bubbles from the Twinstar M3 can now be seen sliding down the front glass. (Being able to visualise the water flow has been a major plus of having that device, and prompted me to improve my flow).

I’m beginning to point the finger at fertilisation. I’ve been dosing TNC Complete, using the 3x dosage which supposedly approximates EI. But I’ve just done some sums, and I’m not sure it does.

According to the analysis of TNC Complete, it contains the following:

N - 1.5%
P - 0.2%
K - 5%

So, taking an imaginary tank of 1,000 litres (i.e. 1,000,000 grammes), the 3x dosage of TNC complete would be 300ml weekly. Therefore our dosage contains the following:

N - 4.5g = 19.9g NO₃⁻
P - 0.6g = 1.8g PO₄³⁻
K - 15g

Now if I understand correctly EI calls for 20ppm NO₃⁻ so the above dosage is indeed correct.

But EI also calls for 3ppm PO₄³⁻ so the above dosage is significantly under.

Likewise, EI calls for 30ppm K so again the above is significantly light.

Is it possible that my plants are deficient in PO₄³⁻ or K? When I do water changes, I use about 10 litres of rainwater with 2 litres of tapwater to get the softness I want, so I’m not getting much contribution from the tap.

Should I increase my dosage of TNC Complete, or should I bite the bullet and start using DIY salts?
 
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Here’s an idea...

What if I simply bought some monopotassium phosphate and dose some of that? Given that the atomic weights of K and P are similar, I’d be adding K and P in roughly equal weights, which would correct the shortfall.

I might even be able to add a suitable amount of it to my bottle of TNC Complete to beef up the K and P dose.
 

Bryce

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Honestly if your tank is only 4 to 5 weeks old be patient. That’s a very young tank. There is more then enough fertilizer in TNC. It takes time. Be happy with nice slow growth as long as plants are healthy and algae is at a minimum.
 
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Honestly if your tank is only 4 to 5 weeks old be patient. That’s a very young tank. There is more then enough fertilizer in TNC. It takes time. Be happy with nice slow growth as long as plants are healthy and algae is at a minimum.
I guess you’re right! I should be thankful that my algae issues are minimal.
 

kilnakorr

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How much TNC do you dose and when (once a week, 3 times a week or other?)
Are waterchanges consistent with 10L rainwater and 2L tap?
 

Zeus.

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EI dosing has a range

NO3 range 5-30ppm
K+ range 10-30ppm
PO4 range 1.0-3.0 ppm
Fe 0.2-0.5ppm or higher (?)
GH range 3 degrees ~ 50ppm or higher

TNC complete is at the lower end of the range but with low light and no CO2 injection it should be plenty and a good easy choice for a 20l tank :thumbup:
 

Sammy Islam

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In a 20L "high tech" tank you should dose approximately 2ml a day of tnc complete to get to the lower end of EI level which should still be enough. You can push it to 3ml a day but tnc complete is heavy on the K compared to other nutrients. So i would definitely start daily dosing at 2ml.
 
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Interesting - thanks for all the replies! :thumbup:

So my current dosage is 1ml per day, every day. This is roughly in accordance with the instructions for TNC Complete, but is less than people have recommended here. The “normal” dose would be 1ml per 10 litres (i.e. 2ml for my tank) once a week, but the instructions say that you can dose this three times a week (i.e. 6ml per week for my tank) to approximate EI. What I do is dose 1ml every day, because I figure that a smaller, more frequent dose is better - and it’s easier to remember! So I’m dosing 7ml a week, which is slightly more than the instructions say.

My tank is definitely “high energy” - I have a lot of light (possibly too much, about 1200 lumen), and CO₂ injection with a bright green drop checker (supplemented with standard doses from an old bottle of Flourish Excel I had lying around, to use it up - don’t know if it’ll still be effective after a year or so).

I have 7 ember tetras, 3 pygmy cories and 2 Amano shrimp. And an unknown number of Asellus aquaticus (thanks for the ID, Darrell!), probably hitch-hikers from some hornwort I transferred from the pond. This will be “it” for at least a while, although a small colony of cherries is a possibility once the tank is a bit more mature.

Water changes are 50% twice a week at the moment. I use 10 litres of rainwater plus 2 litres of tap, giving KH and GH both 4°, which I then supplement with Epsom salts to boost GH to about 7° (to assist shrimp moulting). TDS before a water change is usually about 170, and about 145 after. pH is about 6.5.

According to Rotala Butterfly, it agrees with what several of you have said, that I should indeed be dosing 2ml or even 3ml a day of TNC Complete. I think it suggests 2.5ml a day.

What makes me think I may have a problem is the Hottonia palustris, which I would expect to be romping away. It looks like it’s trying to make new leaves, but they don’t really grow to full size - it looks stunted. That said, I tried adding some Amazon Frogbit earlier this week, and already I’m mildly terrified by the rate at which new leaves are appearing!

I’m minded to go with people’s advice and try upping to 2ml per day and see what happens. I read somewhere (it may have been one of Clive’s posts) that a phosphate shortage can interfere with nitrate uptake, so it seems worth a try to increase everything.

By the way, Clive hasn’t posted for a few years. I hope he’s alright.
 

Zeus.

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kilnakorr

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If the calculations are right: 7mL per week you get a total of:
N: 5.25
P: 0.7
K: 17.5
You do 50% water change twice a week. Meaning a lot less ferts in the tank.
Also, how do you add 12L of new water to a 20L tank and make that 50% (not taking substrate and possible hardscape into the equation)?
 
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You do 50% water change twice a week. Meaning a lot less ferts in the tank.
Very good point. Perhaps I should give an extra ml after each water change.

Also, how do you add 12L of new water to a 20L tank and make that 50% (not taking substrate and possible hardscape into the equation)?
True! The tank is actually 25 litres in size, but displacement brings it down to about 20. In practice I mix up the 10:2 and usually have a couple of litres left over, which I keep in a lemonade bottle and use for topping up.

I’ve read in various places that Rotala walichii may not produce its best colours unless the nitrate level is kept down, so I’ve also been looking at the idea of supplementing the TNC Complete with extra potassium and phosphate, instead of increasing the dose. I’ve worked out how much KH₂PO₄ and K₂SO₄ I’d need to bring the K and P up to a more generous level, and found somewhere I can order them in small quantities. I’ve worked out what I’d need to dissolve into a stock solution which I’d then dose at the same time as the TNC.

I must also look at the iron content of TNC Complete.

Edited to add: Hmmm... by my sums, the recommended triple dose of TNC Complete gives 0.24ppm per week. So that's near the lower end of the EI range. I'll have to watch out for iron deficiencies.
 
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kilnakorr

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I’ve read in various places that Rotala walichii may not produce its best colours unless the nitrate level is kept down
This is true for many 'red' plants.
However, usually when keeping N down in the watercolumn you fertilize the substrate instead. Otherwise you might get in trouble with various deficiencies in both the walichii in other plants.
Some reading on red plants and ferts:
https://www.advancedplantedtank.com/newsletter_2ozn.html
 

Zeus.

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Well TNC advise 1ml per 10litres
may calculater gives for that dose
upload_2020-3-22_15-0-54.png


and rotala advises 5ml for your tank

upload_2020-3-22_15-2-41.png
 
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I’ve just noticed some interesting symptoms on my Anubias nana “bonsai”.

There are various areas of browning, which may in itself point to some kind of deficiency, but there is also some quite distinct veinal chlorosis. Normally, nitrate or iron deficiencies result in intra-veinal chlorosis, where the veins are deep green and the tissue in between is yellow. But this is precisely the opposite - the veins are yellow, and the tissue in between is deep green. This is mainly on older leaves.

What do you think this could be? Any thoughts, Darrel @dw1305?

Apologies for poor zoomed-in iPhone pictures...

B1FE2B41-3E26-4D3C-8FB2-582BE69CF974.jpeg D41271B9-8D05-41FD-A376-BC5A3CFB7B5F.jpeg
 

kilnakorr

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Where in your tank are these located?
It's a ver slow growing plant, and most issues with it is to much light.
 
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Thanks Darrel! I do add Epsom salts during water changes. I reckon it’s abou 12ppm.

Here’s a full tank shot, albeit with distracting reflections. I’ll try and do a better one this evening.

4F53AC7B-D6B0-49C3-B643-4F7D7E417A3D.jpeg
 

dw1305

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Well, since upping my dose of TNC Complete to double the recommended triple dose, I have seen an improvement in the Hottonia palustris. The tips are now looking less “bleached”, and less flattened; I do think it’s growing better.

The Rotala walichii does seem to be turning a bit greener. I think there may be some truth in the assertion that it only goes pink when mildly deprived of nitrogen. To be fair, though, it has grown immensely from the minute tissue culture it started as, and I’ve been able to trim and replant lots of stems - and the cut stems do seem to be producing replacement shoots. I think it may be gradually producing thicker, more luxuriant and feathery growth, although it still has a long way to go to match the pictures that you see online.

The dwarf hairgrass is doing very nicely, and I am gradually trimming that shorter and shorter because I want it to be very low in the foreground.

My HC “Cuba” initially grew really well. But then I got excessively worried about the oily surface film (see this thread), and I started drastically reducing my light intensity. The HC did not take kindly to this, and started going brown at the base and disintegrating. I have lost three-quarters of it, but a combination of factors has halted the decline: I’ve gone back to high light; I’ve improved my flow; and I’ve pushed the remaining HC further down into the substrate. It’s looking a lot better but I may have to buy some more to accelerate the carpeting on the right hand side.

A continuing puzzle is why my Cryptocoryne wendtii isn’t doing anything. It started as a tissue culture, and grew for a week or two - but has hit a brick wall and stopped growing while still rather tiny. It’s not melting; it’s just sitting there doing nothing. Many years ago I had a similar problem with a Crypt that I added to a tank, which grew well for a week or two and then stopped. I have a suspicion that Crypts can utilise stored nutrients for a while, but then when that runs out they just stop. In that instance I tried putting a root tab underneath the plant, and it started growing again within days. So I’m going to try that strategy again, even though my substrate should be nutritious enough.

Likewise, the Lilaeopsis novae-zealandii is not doing a great deal, so I’m going to shove a root tab underneath that as well. Just waiting for some TNC root tabs to arrive. (An Amazon box has just come, so I’m hopeful...).

So, I do think the increased nutrient dose has helped, but I think the next step is to switch to DIY salts, so I can tailor the nutrients myself. I will go for a generous dose of potassium and phosphate, but a slightly less generous dose of nitrate. I’ve now got all the salts I need and have crunched the numbers. I’ll aim for 15 ppm NO₃⁻, 3 ppm PO₄³⁻, and 30 ppm K. And I’ll dose TNC Trace to give 0.5 ppm Fe.
 

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