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Fert dosing vs water change vol for new setup

Anomander

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24 Apr 2024
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Location
London
Hello again all,

My tank setup took a while longer than expected due to life getting in the way. In any case, I now have a Ciano 80 (c. 70 litres) with the bundled 8w light. It is low-tech with a sand substrate, and currently has a mix of Anubias, Java Fern, and Salvinia Minima. It has only been up and running for four days, and I was just wondering about fertiliser dosing when taking water changes into consideration.

I am doing 50% water changes every other day for the first few weeks, and also doing a half-dose of TNC Complete once a week during this period (which works out at about 3-4ml per week). My question is, since I am changing water more often than I am dosing fertiliser, do I need to 'top up' the fertiliser with a smaller amount after every water change, or can I stick to just dosing the 3ml every week after one of the water changes?

I should also add that my lights are currently on a rather limited 4hrs per day as my tank is in a fairly bright room (East facing, no direct sunlight on the tank though) and I cannot dim the 8w LED that came with the tank, which seems rather bright. I'm also conscious of exposing the Anubias and Java to a lot of light whilst the Salvinia grows in.

Thanks very much for any help. Any other comments or advice on my setup is very welcome.
 
Hi
If you are doing regular water changes for the first few weeks and replacing with London tap water, everything should be fine!

You won't even need expensive TNC -C...till later down the road when cutting back on water changes!
One thing you could add is Epsom Salt/MgSo4...as the tap water is usually high in Calcium and low in Magnesium!
Use the below article!
 
Thank you, especially for the Epsom salt tip - I would've never considered that
 
Hi all,
I should also add that my lights are currently on a rather limited 4hrs per day as my tank is in a fairly bright room (East facing, no direct sunlight on the tank though) and I cannot dim the 8w LED that came with the tank, which seems rather bright. I'm also conscious of exposing the Anubias and Java to a lot of light whilst the Salvinia grows in.
Personally I'd put it up to eight hours, it just ensures you have enough <"light to reach LCP">.
Thank you, especially for the Epsom salt tip
It is all down <"to geology">. I always <"add a bit"> of extra magnesium (Mg), it isn't going to do any harm and it costs pennies.
and also doing a half-dose of TNC Complete once a week during this period (which works out at about 3-4ml per week)
What does the <"Salvinia"> look like? If it looks healthy and is growing? You have enough nutrients.

You would need to look a the <"shape of the hairs"> (trichomes), but It is likely to be <"Salvinia "auriculata group">, <"what ever it was called"> when you bought it.

cheers Darrel
.
 
Personally I'd put it up to eight hours, it just ensures you have enough <"light to reach LCP">.
OK, I was doing 4hrs due to the lack of a dimming function, as well as being afraid of algae and harming the low light plants. Should I do the increase gradually?
What does the <"Salvinia"> look like? If it looks healthy and is growing? You have enough nutrients.

You would need to look a the <"shape of the hairs"> (trichomes), but It is likely to be <"Salvinia "auriculata group">, <"what ever it was called"> when you bought it.

Yes, it was the Tropica Salvinia minima (auriculata) 1-2-GROW. To be honest it's only been a few days so I cannot yet notice any discernible difference from when it came out of the Tropica pot. My main worry has been that it's being blown around a bit by the filter outlet. I've taken off the filter's duckbill so the outflow it is no longer pointing directly at the surface, but then I became concerned about oxygenation so added a venturi. The Salvinia is still getting blown around a bit but I'm loathe to lose my remaining flow and surface agitation. I'll try and work out how to post a video of it!

Thanks for all the help, as ever.
 
Hi all,
Should I do the increase gradually?
You can go straight to eight hours, the room already has some ambient light.
but then I became concerned about oxygenation so added a venturi. The Salvinia is still getting blown around a bit but I'm loathe to lose my remaining flow and surface agitation.
I keep going with the flow you have, I'm a <"venturi fan"> as well.

One disadvantage of floating plants (when compared to submerged plants) is that their gas exchange <"is via stomata"> in the adaxial (upper) leaf surface.

You still have the advantages of increased surface area for nitrification and the plants uptake of nutrients with floating plants and they are never CO2 limited, so I still think the pluses massively outweigh the negatives.

cheers Darrel
 
That's good to know, thank you. I will wait a short while to give any deficiencies in the Salvinia time enough to show themselves and report back if there are any issues.
 
I have looked at the thread on adding magnesium and consequently went on the Rotala Butterfly site, where I entered a target of 3.5 ppm. For 60 litres of water this gave me a figure of just over 2 grams of Mg. Does this sound about right, and would it be added weekly? Thanks in advance.
 
I have looked at the thread on adding magnesium and consequently went on the Rotala Butterfly site, where I entered a target of 3.5 ppm. For 60 litres of water this gave me a figure of just over 2 grams of Mg. Does this sound about right, and would it be added weekly? Thanks in advance.
Just toss approx. 2grams in at water Change (WC)
1720561375650.png
 
Hello again,

I've been doing a bit more reading around hard water on this forum (I am on Thames Water in London) - would I need to dose Iron as well as Magnesium? I'm becoming aware that the two are linked but not entirely sure how. I have attached my local water quality report if it is of any help. Thanks again for the help.

E2A: I am using TNC Complete which does contain traces of Mg and Fe, though I'm not sure how sufficient the quantities are to make up for any deficits in my water supply.

 
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That's good; I can see that DTPA is widely available online. Would you also be able to tell me if I would be similarly dosing weekly (like Magnesium), but aiming for less of a ppm than Magnesium (3.5ppm)? Thanks for your help.
 
Hi all,
would I need to dose Iron as well as Magnesium? I'm becoming aware that the two are linked but not entirely sure how.
The common factor is really calcium (Ca++). Our hard water (in the UK) usually has a very high calcium to magnesium (Mg++) ratio, this means that <"plants may struggle"> to take up magnesium ions.

This same effect also applies to iron (Fe++(+)) ions, but you also have the double whammy of the <"hard, alkaline water"> having a lot of anions (HCO3-, OH- etc) that combine and <"form insoluble compounds"> with iron ions.

To keep iron plant available, at high pH and hardness levels, we need to use a chelator, like FeDTPA.

cheers Darrel
 
To keep iron plant available, at high pH and hardness levels, we need to use a chelator, like FeDTPA.
Thank you for your input. So am I correct in thinking that a chelator like FeDTPA is different from the Fe that is contained in the TNC Complete, and that the former helps the plants to uptake the latter? Apologies for all the questions, I am trying my best to understand and give my plants a healthy environment but I'm also from a non-scientific background.
 
Hi all,
So am I correct in thinking that a chelator like FeDTPA is different from the Fe that is contained in the TNC Complete, and that the former helps the plants to uptake the latter?
It should say what the chelator is on the label? FeEDTA is the "normal one", but it may not be effective in harder water.

FeEDDHA, or FeDTPA, would be better than FeEDTA. You can buy a chelate blend for home gardeners as <"Chempak (or Vitax) Soluble Iron">.

All plants (including terrestrial succulents etc) can ~only take up nutrients as "ions", charged particles in solution. The problem with iron (Fe) is that if we just add a soluble compound compound (like <"ferric chloride"> (FeCl3)) those Fe+++ cations will be <"mopped up almost instantly"> by OH-, PO4---, HCO3- etc anions and these <"insoluble compounds"> will precipitate out of solution.

As soon as iron <"isn't plant available">? New leaves become yellow and chlorotic.
This iron deficient Amazon Frogbit (Limnobium laevigatum) (thank-you to @jameson_uk for the photo, from <"Duckweed Index says Nitrogen please?">). I'm sure @jameson_uk won't mind me mentioning that he is <"red-green colour blind"> and colour blindness does cause an extra level of complexity in judging "greeness".

dad12186cb152cccee11028dc11c34f4-jpg.jpg
Iron chelators were initially developed for commercial hydroponics and are photodegraded by light to <"let a continual trickle of iron ions"> become plant available. Plants can't move iron around, so it is only new leaves, produced once iron ions are plant available, that will be healthy

cheers Darrel
 
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Ah, I follow. Thank you for the info, and the chelate blend recommendation. Armed with this info and the nutrient dosing calculator I think I'm beginning to get my head around this.
 
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