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DIY all in one fertiliser solution going cloudy

Rapayich

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I have been messing around with making my own all-in-one fertiliser mix over the past few months but can't seem to get it right. In my solutions I am using:

KNO3
KH2PO4
MgSo4
DTPA Iron 11%
Copper sulphate (Unchelated)
Manganese sulphate (Unchelated)
Boric Acid (Unchelated)
Zinc Sulphate (Unchelated)
Sodium Molybdate (Unchelated)
Potassium Sorbate
Ascorbic Acid
RO Water

Before adding the salts I ensure the water has been acidified to about 2.5pH. I also ensure that the macro and micro solutions are fully dissolved before combining. The solution remains clear for about 2 weeks but then goes cloudy. Note that no precipitate can be seen but it definitely goes cloudy throughout the whole solution. Does anyone have suggestions regarding this issue. Maybe the cloudiness is not a problem and is moreso some sort of bacterial buildup? My RO unit is very old but can still produce water around TDS 5. Solutions are kept at room temp and in a dark container away from sunlight.

Cheers!
 

Courtneybst

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@Happi
I see 2 drawbacks with the above procedure though:
1. One would need to add the iron 11% first to acidify the water before adding other compounds. This is not ideal since it makes it difficult to see any potential precipitate that might happen during the addition of subsequent compounds. This is why @X3NiTH advises adding it at the end.

2. One can only use 11% Fe or above or chelates that do not bring the PH up. In the case of @Courtneybst he is also using APFUK traces which contain 8% and will raise the PH.

This is why we always advise in the IFC calculator in acidifying the water prior adding anything and why ascorbic acid is recommended. This said your way is an alternative and could be used in certain case scenarios.
In this case, would you recommend still using ascorbic acid initially to acidify the water and add the 11% DTPA at the end? Or should I now forego one for the other?

Thanks
 

ian_m

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In my experience you do actually need both a preservative and acidifying agent, or else, in my experience, either the iron un-chelates and liquid goes "rusty" and a precipitate forms, or the solution just goes mouldy. The acidifying agent, ascorbic acid normally, is needed usually potassium sorbate, works best in acid conditions. Also make sure you use RO or distilled or possibly cooled boiled water, as if you use "harder" tap water it will react with the ascorbic acid raising the pH and nullifying the effect of any preservative used. Or just add more ascorbic acid to be sure.

Anyway, I had some solution I forgot to add acid to and it went rusty and cloudy, from the originally mixed up transparent'ish green. But I dosed it anyway, when the CO2 was on and tank water was likely to be acidic'ish. My theory was the cloudy iron precipitate would react with acidic water to become soluble iron that plants could use. Anyway plants didn't appear to suffer in the couple of months it took to get rid of the cloudy solution.
 

Hanuman

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In this case, would you recommend still using ascorbic acid initially to acidify the water and add the 11% DTPA at the end?
In my opinion, yes you should acidify the water prior adding anything because your PH might be borderline neutral with the APFUK trace and the 8% iron in it. I can't say for sure but better be safe than sorry. The ascorbic acid wont hurt anyway. You could try with a smaller batch see how that goes. This is the order I would follow if it was me:

Water > Ascorbic acid+Potassium sorbate > Macros > Fe 11% DTPA > APFUK traces

It is possible that the Fe 11% DTPA might acidify the water enough but I have my doubts hence better be safe. If you didn't use APFUK trace mix which contains 8% Fe and instead you used individual un-chelated traces then you could do it the @Happi way by adding the Fe 11% DTPA first to acidify the water and then adding the rest. The cherry on the cake would be the sodium benzoate to preserve the mix long term.
 
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Sodium Benzoate sounds like a scary substance from what I’ve read ( I avoid any foods that have it listed in the ingredients).
I might use it in a plants only aquarium but as I have inmates in both of mine it’s not something I’d use.
 

Andy Pierce

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In the 'because it's easy' category, I acidfy using acetic acid (2 ml vinegar) with potasssium sorbate (1/8 tsp) as a preservative per 500 ml stock solution - I add to both a bottle of macros and to a separate bottle of chelated trace. I haven't noticed anything obviously problematic about using vinegar but would in interested in opinions.
 

X3NiTH

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Acidify the receiving water first, always! Adding an FeII compound to neutral pH water containing oxygen there’s going to be an oxidation reaction and while the pH may drop significantly a chunk of FeII is going to be converted to FeIII, FeIII is more acidic than FeII, at some point the reaction stops and you’ll have a stable solution of low pH being a mix of FeII and FeIII.

If using a Benzoate compound for preservation I’d prefer using Potassium Benzoate over Sodium Benzoate if I were avoiding Sodium. I would also not use Ascorbic Acid for acidification due to Benzene formation which is a Carcinogen with Teratogenic and Neurogenic side effects (the risk is to fauna in the aquarium).

My recommendations for unchelated micronutrient mixes are to use receiving water that is exceptionally low in TDS (ideally Zero) and acidified to below pH4 before any salt addition. I refrigerate my mix and decant to the dosing container when needed. I use dosing bags as my containers (novelty Bloodbags for Vampire Halloween costumes) this helps prevent long term oxidation reactions within the mix due to atmospheric oxygen which in turn hopefully starves bacterial and fungal growth. I don’t add preservatives to my mix, I want it fresh without unnecessary additives, short term longevity is all I need (2-3 months stability outside refrigeration).

The more concentrate your unchelated mixture the greater the chance for precipitative effects and depending on the ratios of compounds going into solution there may be a charge balance discrepancy and in order for electrically neutral water to balance the charges an amount of precipitation of compounds is guaranteed.

:)
 

dw1305

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Hi all,
The more concentrate your unchelated mixture the greater the chance for precipitative effects and depending on the ratios of compounds going into solution there may be a charge balance discrepancy and in order for electrically neutral water to balance the charges an amount of precipitation of compounds is guaranteed.
That one.

cheers Darrel
 
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Acidify the receiving water first, always! Adding an FeII compound to neutral pH water containing oxygen there’s going to be an oxidation reaction and while the pH may drop significantly a chunk of FeII is going to be converted to FeIII, FeIII is more acidic than FeII, at some point the reaction stops and you’ll have a stable solution of low pH being a mix of FeII and FeIII.

If using a Benzoate compound for preservation I’d prefer using Potassium Benzoate over Sodium Benzoate if I were avoiding Sodium. I would also not use Ascorbic Acid for acidification due to Benzene formation which is a Carcinogen with Teratogenic and Neurogenic side effects (the risk is to fauna in the aquarium).

My recommendations for unchelated micronutrient mixes are to use receiving water that is exceptionally low in TDS (ideally Zero) and acidified to below pH4 before any salt addition. I refrigerate my mix and decant to the dosing container when needed. I use dosing bags as my containers (novelty Bloodbags for Vampire Halloween costumes) this helps prevent long term oxidation reactions within the mix due to atmospheric oxygen which in turn hopefully starves bacterial and fungal growth. I don’t add preservatives to my mix, I want it fresh without unnecessary additives, short term longevity is all I need (2-3 months stability outside refrigeration).

The more concentrate your unchelated mixture the greater the chance for precipitative effects and depending on the ratios of compounds going into solution there may be a charge balance discrepancy and in order for electrically neutral water to balance the charges an amount of precipitation of compounds is guaranteed.

:)
Sounds good. 👍If you get a moment perhaps you’d do a tutorial or a “dummies” guide of your process? We like pictures as well so feel free to add anything you feel relevant.
 

Happi

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Potassium Benzoate over Sodium Benzoate if I were avoiding Sodium
Never tried the potassium Benzoate before so can't comment on that but sodium from 0.3 gram sodium benzoate only adds about 0.01 ppm Na if the solution was based on 500 ml, 20 ml per 50 gallon.

Other chelated salt adds much more Na than Sodium Benzoate that we use for our stock solution.
 

Hanuman

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Done my due. Ready for the next century. @Happi .
IMG_9017.JPG
 

plantnoobdude

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Just a thought but could you use Citric Acid instead of Ascorbic Acid and/or Potassium Sorbate in an AIO mix?
@Hufsa has tried this.
I have as well, I use 0.45grams per liter I think based on a conversation with her.
 
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Thanks, I may try that next time. 0.45g per litre sounds a bit low? The recipe I follow uses 0.5g of Ascorbic Acid and 0.2g of Potassium Sorbate for a 500ml mix.
This is the full recipe:
10g Potassium Nitrate
2.3g Monopotassium Phosphate
4.0g Potassium Sulphate
8.0g Magnesium Sulphate Heptahydrate (Epsom Salts)
0.5g E300 Ascorbic Acid
0.2g E202 Potassium Sorbate
6g EDTA Chelated Trace Elements Mix (TNC Trace, CSM+B)
500ml distilled water
 

Hanuman

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Just a thought but could you use Citric Acid instead of Ascorbic Acid and/or Potassium Sorbate in an AIO mix?
Yes you can. You can also use vinegar if you fancy that. That's what @GreggZ does or if you are a lab enthusiast, you can use some sulfuric acid, but we all know the dangers involved with strong acids.
 
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