New Fert Time and Confused... (Sulphur Levels?)

jameson_uk

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TL;DR - A few questions about mixing ferts for a low / medium energy tank (no CO2)
  • Is NO3- 10 / K - 10 / PO4 - 1 a sensible target
  • What mix of salts can i use to get somewhere near this
  • Should I account for high nitrates out the tap
  • can I add EDDHA straight into this all in one mix on top of the CSM+B without issue
I am on my last lot of ferts so I need to make some more up.
I have had some issues with my Frogbit (which I think has been resolved by extra ferts and iron) but I am now seeing issues with my Hygrophila which I suspect is a lack of Potassium / Phosphate.

I have been mixing up the DIY TPN+ (3) recipe from http://www.theplantedtank.co.uk/allinone.htm and dosing roughly as per Tropica's recommendation.

Putting this into various calculators and it looks like I am adding in the region of
NO3 - 6.541867 ppm
K+ - 4.265258 ppm
PO4 - 0.341196 ppm

Now attempting to look at what levels I probably should be adding I came across a few views from 1/5th EI levels right up 1/2. Rotala does have a weekly EI low tech option which looks to come out with targets of
  • NO3 - 10 ppm
  • K+ - 10 ppm
  • PO4 - 1 ppm
and taking say 1/5th EI levels I guess this would be
  • NO3 - 1-6 ppm
  • K+ - 2-6 ppm
  • PO4 - 0.2 - 0.6 ppm
which the levels I am adding are in so I guess I need more.

So I started looking at tweaking the recipe (and I can hear Clive saying this is asking for trouble already) but not sure where to start as I can't seem to get anywhere near the 10/10/1 levels; Mainly the K as getting that near 10 raises the NO3 and PO4 (and depending on salts SO2) levels way above these levels.

On top of that my tap water is already high in nitrates (The average in my area is 23 ppm and I think that is indicative if my water) so once you start accounting for the levels out the tap and my 50% weekly water change, @Zeus. 's spreadsheet says I am adding 17.4 ppm which is already almost full EI levels so adding more KNO3 to increase K doesn't seem ideal (and I guess I kind of want to drop the amount of nitrates I am adding to account for this). I am reluctant to just increase dosing for the same reason (would need about three times the dosage which would then equate to an extra 30.5 ppm of NO3 a week)

The only combination I have found includes adding a lot of K2SO4 which gets near those target levels but increases S to 1.7 ppm which is obviously quite a lot higher than the 0.4 ppm levels of the existing solution.
This also increases the N to 2.2 ppm from 1.5 ppm in the Tropica mix and P to 0.34 from 0.11 but I am not sure what happens to these as they seem to be ignored in the calculators but Rotala shows this as a result of adding KNO3 / KH2PO4.
 

Zeus.

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Is NO3- 10 / K - 10 / PO4 - 1 a sensible target
IMO -yes

What mix of salts can i use to get somewhere near this
KNO3, KH2PO4 and K2SO4

Should I account for high nitrates out the tap
Been chatting with @dw1305 about this recently as it happens
Yes I’d try reducing the nitrogen addition. If it doesn’t work you can just up the amount again.

I don’t really see down-side.
I've recently starting missing the first macro dose after WC as the WC just dumped a load of NO3 in the tank, then Micro,macro,Micro,macro,Micro,macro on following days. as the Macro dose of NO3 has been reduced after allowing for the NO3 in the tap water, so effectively spreading the NO3 over more days

can I add EDDHA straight into this all in one mix on top of the CSM+B without issue
I cant see their being an issue

I can't seem to get anywhere near the 10/10/1 levels; Mainly the K as getting that near 10 raises the NO3 and PO4
Been there and got Potassium Sulphate K2SO4 which resolved the issue , cheap as chips off the net also

The only combination I have found includes adding a lot of K2SO4 which gets near those target levels but increases S to 1.7 ppm
Yes the /[SO4] increases but I dont think thats a issue
 

jameson_uk

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Been there and got Potassium Sulphate K2SO4 which resolved the issue , cheap as chips off the net also
Yes the /[SO4] increases but I dont think thats a issue
KNO3 is currently my main source of K so reducing that means quite a jump in other sources.

The mix that seems to meet the numbers taking into account the NO3 fro the tap (ignoring Mg and micros) is
  • 10g KNO3
  • 6.6g KH2PO4
  • 88g K2SO4
which I believe would give me weekly values of (500 ml solution and 20ml dose into a 180l tank)
  • 1.36 ppm NO3
  • 10.06 ppm K
  • 1.02 ppm PO4
Given my tap water contains about 20 ppm NO3 this would bump up the weekly NO3 dosage to about 12 ppm.

But anything over 49g on the Rotala calculator gives me a warning about the solubility of K being 120 and needing to reduce my does (which I guess means dilute and dose more?).

This however gives 3.83 ppm S which is way higher than the other mixes but I cannot seem to find any info on what values are safe / desirable. I don't really fancy a tank smelling of Sulphur :p
 

Zeus.

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But anything over 49g on the Rotala calculator gives me a warning about the solubility of K being 120 and needing to reduce my does (which I guess means dilute and dose more?).
Or put half the salts in and dose double the amount, How long does your mix last ? better if make a fresh batch every 4-6weeks ( Your post has just reminded me of the solubility limits I've added for the salts to my calculator and not released it yet :banghead: must get that version out :angelic:)

My tank doesn't smell of sulphur, just ran your salt mounts though my Calculator to compare your dose with mine solubility wise, if we both used the same container and dose volume 500ml and 20ml

upload_2020-4-13_20-54-58.png

My Macro mix is in the 'Headshot' column and yours is the DIY Macro, but my NO3 weekly dose was aiming at 20ppm NO3

But when I use my 1.0 litre dosing bottle and 100ml dose

upload_2020-4-13_21-0-40.png

Solubility issue sorted, plus acts as auto top-up as well ;)

Oh and report for your salts is
upload_2020-4-13_21-10-59.png


you could always dose the K2SO4 manually
 
Last edited:

Sammy Islam

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IMO -yes



KNO3, KH2PO4 and K2SO4



Been chatting with @dw1305 about this recently as it happens


I've recently starting missing the first macro dose after WC as the WC just dumped a load of NO3 in the tank, then Micro,macro,Micro,macro,Micro,macro on following days. as the Macro dose of NO3 has been reduced after allowing for the NO3 in the tap water, so effectively spreading the NO3 over more days



I cant see their being an issue



Been there and got Potassium Sulphate K2SO4 which resolved the issue , cheap as chips off the net also



Yes the /[SO4] increases but I dont think thats a issue
I like this reverse alternating dosing idea. Especially as there will be macros left over, also with whatever is being added in with the WC. Would mean the FE would be available sooner for me as i do water change sunday evening at end of photoperiod and i dose starting from monday because of auto-doser programming. Thanks @Zeus. I'm going to give this a shot.
 

jameson_uk

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So I need to mix up some ferts but I am still slightly wary of the Sulphur levels.
I cannot do the chemistry to work it out but I see my tap water has about 50 ppm SO4 anyway so I am already increasing the SO4 levels by 25 ppm per week. This I believe breaks to down to Sulphur so am I already way ahead of 3 ppm anyway?
 

dw1305

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Hi all,
I cannot do the chemistry to work it out but I see my tap water has about 50 ppm SO4 anyway so I am already increasing the SO4 levels by 25 ppm per week. This I believe breaks to down to Sulphur so am I already way ahead of 3 ppm anyway?
You don't need to worry. It will remain as SO4-- ions in solution. It is actually quite difficult to remove sulphates from water.

You have higher levels than most people in the UK will have, probably because your aquifer draws some water from <"evaporite deposits"> (from the "magnesium in tap water thread"). I just looked and Burton upon Trent water has <"about 800 ppm SO4--">.

I've drunk <"Bath"> and <"Lisdoonvarna spa water"> and they are both incredibly disgusting, I couldn't find figures for Lisdoonvarna, but Bath is over 1000ppm SO4--.

Have a look at <"Lenntech - Sulfates"> website as well.

cheers Darrel
 

jameson_uk

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Hi all, You don't need to worry. It will remain as SO4-- ions in solution. It is actually quite difficult to remove sulphates from water.
So no concerns about SO4 building up then? Looking at the accumulation calculator, adding 55 ppm a week, doing a 50% water change and none actually being used by the plants and levels would plateau at ~ 110 ppm. What I can't figure out is how much SO4 I get from K2SO4. The calculator breaks this down to K and S.

You have higher levels than most people in the UK will have, probably because your aquifer draws some water from <"evaporite deposits"> (from the "magnesium in tap water thread"). I just looked and Burton upon Trent water has <"about 800 ppm SO4--">.
The most pronounced aspect of the water from Burton-on-Trent is the sulfate level. At 801ppm (some sources say 820ppm) those sulfates are enough to have a mild laxative effect
:confused: I think even the brewers in Burton now Butonise their water. I can't quite resolve the acronym but the water report talks about samples contravening PCV and PCV for SO4 is 250 ppm. I guess this is now the allowed level in drinking water.
 

dw1305

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Hi all,
I guess this is now the allowed level in drinking water.
It is, down from 500ppm.
So no concerns about SO4 building up then?
Not really, you already have hard, solute rich, water.
What I can't figure out is how much SO4 I get from K2SO4
Easy enough, you need to add together all the <"RAMS to get your RMM">, so (39.1 x 2) + 32 + (16 x 4) = 174 of which 96 (32 + 64) is the SO4. So the percentage of SO4 is 96/174 = 55% SO4.

cheers Darrel
 

jameson_uk

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Ok made up a batch with this recipe (partly for my memory)

0.5g Ascorbic Acid
0.2g Potassium Sorbate
5g KNO3 - Potassium Nitrate
3.3g KH2PO4 - Potassium Phosphate
44g K2SO4 - Potassium Sulphate
4g MgSO4.7H2O (Epsom Salts)
2.8g APF Micro Mix
3.2g 7% EDDHA FE

and 500ml distilled water.

Doses at 40ml a week in 180l and takes into account that my tap water contains ~20-25 ppm NO3 and I do 50% weekly water changes.

So should give me about
1.36 ppm NO3 (+ ~10ppm from tap water)
10ppm K
1ppm PO4

Doesn't give me much Mg but it turns out my tap water contains a reasonable amount anyway.

Mix looks like this which made me unsure whether the EDDHA had reacted with the phosphate or not?
b7780584fd0fe6cd31bdaf56a442a62a.jpg
 

Jayefc1

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That dont seem right to me either looks very dark
I make all in one but dont use EDDHA dont feel my tanks have a iron issue I'm close to burton on trent to swadlincote so not sure if our tap water is similar
Also the MGSO4 seems well short my mix to get the ppm is 60grams
I don't take into account my tap water though but as long as your doing your water changes my mix is pretty close to the denise wong ppms
 

jameson_uk

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That dont seem right to me either looks very dark
I make all in one but dont use EDDHA dont feel my tanks have a iron issue I'm close to burton on trent to swadlincote so not sure if our tap water is similar
Also the MGSO4 seems well short my mix to get the ppm is 60grams
I don't take into account my tap water though but as long as your doing your water changes my mix is pretty close to the denise wong ppms
It looks like your water comes from Leicester way. (https://www.stwater.co.uk/my-supply/water-quality/check-my-water-quality/). I did think yours came from the Trent somewhere near Long Eaton but looking at the hardness I guess not.... Severn Trent annoyingly don't supply hardness details like South Staffs so you don't get a breakdown of how the hardness is made up.

My old place is five miles south of here (supplied by Severn Trent) and there is quite a difference. The water there has a GH of ~2 where as mine is ~12.

The Iron looks very dark when just mixed up with water.
MVIMG_20200419_112923.jpg
 

jameson_uk

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I am colourblind but the misses has assured me the tank is water coloured not pink.

I am only dosing once a week but this was two days ago.

Does this mean the iron has gone? If it isn't remotely pink after dosing does that mean the iron is no longer in solution?

Could the fact the all in one mix is meant to be at pH 6 cause any issues?
a7c098e1ebe114a6723fc540b7492e2b.jpg
51b0dbcbd782a1f7555aa7b4081dbb94.jpg
 

dw1305

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Hi all,
I am only dosing once a week but this was two days ago. Does this mean the iron has gone? If it isn't remotely pink after dosing does that mean the iron is no longer in solution?
Plant growth still looks pretty good, so I don't think you have anything to worry about.

Is it a <"Loquat leaf"> in the tank?

cheers Darrel
 

jameson_uk

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Hi all, Plant growth still looks pretty good, so I don't think you have anything to worry about.
It does but I did remove quite a lot of unhealthy leaves over the weekend and there are still patches of frogbit which look as if they are iron deficient. I have mind of accepted I will never be able to supply enough ferts to keep them 100% happy but just wanted to make sure that some (usable) iron is actually getting added to the tank so I don't end up where the frogbit started to turn quite bad.

Is it a <"Loquat leaf"> in the tank?
Nothing that exciting. It is a couple of Catappa (Indian Almond) leaves. Which reminds me I have some oak leaves I was going to add....
 

Sammy Islam

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Since i started using EDDHA the tank only goes slightly pink, it's not that noticeable looking straight at the tank, but can definitely see a pink tinge when looking through the tank from the side.
 
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