Adding Potassium Sorbate to EI mixes . . .

Wookii

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I have been advised when mixing larger batches of pre-mixed EI salts in solution - designed to be used over an extended period of time - to add a 'pinch' of Potassium Sorbate to the mix. As I understand it, Potassium Sorbate is a preservative, and is added to prevent the mix going bad over a longer usage duration.

I plan to mix 1.5 litre batches of micro and macro mixes, which should last around 40 weeks on our new 60 litre aquarium, using an auto-doser to dose 12ml of each, every other day.

What I wanted to check is that adding this Potassium Sorbate is not going to be detrimental to fish, inverts, or the tanks biological system?

I'm assuming not, as a) the person suggesting it surely knows what they are doing, and b) a 'pinch' in 1.5 litres is a very tiny amount relative to 12ml dosage per day and the tank volume. However these things are always worth checking!?
 

papa_c

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Reading on this previously my understanding is that you should use 1g per litre of liquid in conjunction with acetic acid to drop the ph. I've used it for my mix but strangely my ei mix turns brown but no signs or mold is visible.

My latest batch I have just mixed with macro salts to see if it has a negative effect.

As a tip I sterilize my container with baby sterilizing fluid prior to mixing it up.
 

MJQMJQ

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Reading on this previously my understanding is that you should use 1g per litre of liquid in conjunction with acetic acid to drop the ph. I've used it for my mix but strangely my ei mix turns brown but no signs or mold is visible.

My latest batch I have just mixed with macro salts to see if it has a negative effect.

As a tip I sterilize my container with baby sterilizing fluid prior to mixing it up.

Oxidation?
 

papa_c

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Really no idea why!

One thing I noticed was when mixing K2SO4 in hot water to dissolve it, this turned light brown colour immediately....never experienced this in cold water.

When I add 500ml to 70g of K2SO4 it 'fizzes' wildly.

Any chemists out there that could give an educate reason? Has this affected the potassium availability?
 

MJQMJQ

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Oxidation or reduction will change colour of solutions.Potassium is not a transition metal.Precipitation or displacement?fizzing generally is reaction btw acid and metal or metal carbonates releasing gas.Hot water has more energy hence fueling the reaction perhaps.Any other chemicals in there?Brown seems like iron ions or precipitate.Is the water murky or has any obvious particles?
 

dw1305

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Hi all,
One thing I noticed was when mixing K2SO4 in hot water to dissolve it, this turned light brown colour immediately.
Interesting, I wonder if the colour is actually an iron compound. Ferric sulphate ((Fe2(SO4)3)) solution is light brown/yellow and that would be my guess, what nay have happened is iron ions present in the warm water reacting with the sulphate ions (from the dissolution of the K2SO4). Reaction rate increases with temperature for most reactions, or it may be the hot water has iron ions present and the cold water doesn't.

Do you know how hard your water is? If it was soft then a reaction involving iron ions is a lot more likely.
Has this affected the potassium availability?
It definitely hasn't affected the potassium availability, potassium salts are nearly all soluble.

cheers Darrel
 

jaypeecee

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I have been advised when mixing larger batches of pre-mixed EI salts in solution - designed to be used over an extended period of time - to add a 'pinch' of Potassium Sorbate to the mix. As I understand it, Potassium Sorbate is a preservative, and is added to prevent the mix going bad over a longer usage duration.

I plan to mix 1.5 litre batches of micro and macro mixes, which should last around 40 weeks on our new 60 litre aquarium, using an auto-doser to dose 12ml of each, every other day.

What I wanted to check is that adding this Potassium Sorbate is not going to be detrimental to fish, inverts, or the tanks biological system?

I'm assuming not, as a) the person suggesting it surely knows what they are doing, and b) a 'pinch' in 1.5 litres is a very tiny amount relative to 12ml dosage per day and the tank volume. However these things are always worth checking!?

Hi @Wookii

I think the source of the potassium sorbate addition may have come from a site called James' Planted Tank. Although this site no longer exists, it can be accessed from another site called Internet Archive Wayback Machine:

http://web.archive.org

It is not a secured site but you are not required to divulge any personal information. I have used it many times as have others that I know. It can sometimes be a tad slow but, when you're in, just search for James' Planted Tank. When you get to the site, select 'Dosing Methods' and then 'All In One Solution'. There, you should find the information that you require.

JPC
 

Andrew Butler

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Although this site no longer exists, it can be accessed from another site called Internet Archive Wayback Machine:
Here's both the direct links:
http://www.theplantedtank.co.uk/allinone.htm
http://theplantedtank.co.uk/EI.htm

Just remember that the following ratios apply; assuming 500ml water
500ml water : 0.5g E300 Ascorbic Acid
500ml water : 0.2g E202 Potassium Sorbate

I wanted to check is that adding this Potassium Sorbate is not going to be detrimental to fish, inverts, or the tanks biological system?
I had this question before along with others, this thread doesn't directly relate but think raises a good question to why people don't use an all in one although mix. I don't think that's what your looking to do though. The ascorbic acid is there to lower the PH for the all in one. @Zeus. I think uses Potassium sorbate in his mixes and it keeps his doser pipes clean - he might comment and let you know but just use the ratio above so for each of your 1500ml / 1.5L you want .5g Potassium sorbate. :)
 

Wookii

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Hi @Wookii

I think the source of the potassium sorbate addition may have come from a site called James' Planted Tank. Although this site no longer exists, it can be accessed from another site called Internet Archive Wayback Machine:

Here's both the direct links:
http://www.theplantedtank.co.uk/allinone.htm
http://theplantedtank.co.uk/EI.htm

Just remember that the following ratios apply; assuming 500ml water
500ml water : 0.5g E300 Ascorbic Acid
500ml water : 0.2g E202 Potassium Sorbate


I had this question before along with others, this thread doesn't directly relate but think raises a good question to why people don't use an all in one although mix. I don't think that's what your looking to do though. The ascorbic acid is there to lower the PH for the all in one. @Zeus. I think uses Potassium sorbate in his mixes and it keeps his doser pipes clean - he might comment and let you know but just use the ratio above so for each of your 1500ml / 1.5L you want .5g Potassium sorbate. :)

Thanks - yes, I'm not combining macro and micro in a single mix - I'll be mixing and dosing them separately - I just need to ensure they stay good (and effective) for the best part of a year once mixed. So I wouldn't need the Ascorbic Acid then? Just the Potassium Sorbate, which I've managed to pick up a lifetimes worth off Amazon for a few quid.

Any suggestions of what 0.5 grams equates to in volume - i.e. using measuring spoons?
 

jaypeecee

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Any suggestions of what 0.5 grams equates to in volume - i.e. using measuring spoons?

Hi @Wookii

The density of potassium sorbate is 1.363 g/cm3. So, you may be able to calculate it from that. But, why bother when you can buy a jewellery scale from Amazon for less than 20 quid? That's what I use for preparing a whole range of chemical mixtures for my fishkeeping. Measuring spoons! They're for baking, aren't they?

JPC
 

Andrew Butler

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So I wouldn't need the Ascorbic Acid then?
It's cheap enough and won't do any harm so why not add it; works as an anti oxidant too.
Someone with a scientific brain might give you a better answer but if it's not going to do any harm and possibly do some good then I'd use it and have before, the link below is for the all in one but explains things a little
http://www.theplantedtank.co.uk/allinone.htm
I asked almost this exact question a while back so have a read of this one. ;)

Just have a google although I'm sure answers will vary slightly about the conversion
 

Wookii

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Hi @Wookii

The density of potassium sorbate is 1.363 g/cm3. So, you may be able to calculate it from that. But, why bother when you can buy a jewellery scale from Amazon for less than 20 quid? That's what I use for preparing a whole range of chemical mixtures for my fishkeeping. Measuring spoons! They're for baking, aren't they?

JPC

Hey, I like to bake too! lol (joking) . . .More seriously though, the EI salt mixing directions from APFUK all use measuring spoon directions (in teaspoons!). As much as £20 is a good price, I'll pass for measuring 0.5g once a year lol

So at 1.363 g/cm3, 0.5g is 0.37 cm3 which is a little over 1 pinch with is 0.31 cm3 (seriously I have spoons to measure a pinch, a dash and a smidgen :lol: )

What are the possible consequences of adding too much Potassium Sorbate - say you doubled up in error (1.0g per 1.5 litres rather than 0.5g)?
 

Wookii

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It's cheap enough and won't do any harm so why not add it; works as an anti oxidant too.
Someone with a scientific brain might give you a better answer but if it's not going to do any harm and possibly do some good then I'd use it and have before, the link below is for the all in one but explains things a little
http://www.theplantedtank.co.uk/allinone.htm
I asked almost this exact question a while back so have a read of this one. ;)

Just have a google although I'm sure answers will vary slightly about the conversion

OK, fair enough - it looks like I can get a lifetime supply of Ascorbic Acid for less that a tenner also, so I'll add that to the mix! 1.5 g to my 1.5 Litre mix?
 

Andrew Butler

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If you look at this link and read through it will tell you what they've used in the mix; which everything I've written is based on.
use the ratio above so for each of your 1500ml / 1.5L you want .5g Potassium sorbate.
*important note - this was a mistype and I had meant to write 0.6g Potassium sorbate in 1.5L water
0.2g Potassium sorbate in 500ml water (x3 for 1.5L = 0.6g Potassium sorbate)
The same would be applicable for the Ascorbic Acid if you go by the link
0.5g Ascorbic Acid in 500ml water (x3 for 1.5L = 1.5g Ascorbic Acid)

Just have a double check I've written thing correct and they agree with the link below
http://www.theplantedtank.co.uk/allinone.htm
 

papa_c

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Do you know how hard your water is? I

Hey Daryl,

Water is rock hard cambridgeshire water. Last time I checked out of the tap kH was around 18 based on a hobby test kit.

I have a plumbed in RO unit in the kitchen and use this for mixing my macros and micros. Good to know that it hasn't impacted the chemistry.

Any other chemicals in there?

When mixing up my macros I mix kno3, mgso4, and kh2po4 at the same time in one container. Dissolve k2so4 in it's own container and them mix these together. I do it this way as I had some strange reaction when dissolving them all at the same time. I ended up with a lot of flocculation.
 

Wookii

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Another quick question - I've been using my micro and macro mix now since Christmas, but I noticed the other day that my macro mix, which started off completely clear, now has a slightly brown discolouration as mentioned by papa_c above. Not as brown as the micro mix, but certainly well from being clear. I see nothing else in the container to suggest mould or other issues.

Is this something to be concerned about, and might it reduce the effectiveness of the mixture? It's worth noting that a separate mix I did in the standard UKAPF container, is still clear after two months - the only difference between them is the addition of the Ascorbic Acid in the now-discoloured mix.
 

papa_c

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Hey Wookii,

I never managed to understand the brown reaction. I now don't add either potassium Sorbate or ascorbic acid to my macro and micro.

Between making each micro and macro mix I simply sterlise the containers with cheapo baby fluid. Haven't had any issues with mold growth based on a making up a months mix at a time.
 

ian_m

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I now don't add either potassium Sorbate or ascorbic acid to my macro and micro.
You ought to really add at least ascorbic acid as that keeps the pH low (as well as helping the anti-fungicide of potassium sorbate work correctly) and keeps the chelates chelated. See graph below of how chelation changes with pH.
upload_2017-3-22_16-59-44-png.png


Most micros, commonly used as aquatic ferts are EDTA (Ethylene-Diamene-Tetra-Acid) and will unchelate and be bio unavailable to plants, if the pH rises much above 7 ie neutral. Hard water, depending on hardness, has a pH of above 7, maybe even 8.5, in which case if used, the chelate will all come out of solution and be unavailable for plant use.
 

papa_c

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You ought to really add at least ascorbic acid as that keeps the pH low (as well as helping the anti-

Thanks Ian

I use DPTA FE in the micro mix, Is this still required if I use RO water for dilution?
 
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