Macro mix stability

[blairgerman]

Hi, my macro mix becomes unstable with some white algae substance and stuff falling out of solution after about 1 week or less. I have another channel on my doser and I'm wondering if I remove one compound from the mix and put it in another dosing container, this would increase the shelf life. I suspect Potassium Nitrate would be the candidate. Currently it's (85g) KNO3 , (60g) K2SO4 , (10g) KH2PO4 , (30g) MgSO4 into 1L distilled (which is split across this tank and several others.) See parameters below, also journal. TLDR: 1) Which compound to remove? 2) Also, can I use ascorbic or p sorbate in my macros mix for shelf life? Thanks for your time and consideration.

 

[John q]

stuff falling out of solution after about 1 week or less.

All of the salts are within there solubility levels, but combined it maybe exceeding those levels. Acidifying the mix will increase solubility, and maybe deter mould?? . Personally I'd half the strength of your mix and accept it needs mixing more frequently.

 

[dw1305]

Hi all,

unstable with some white algae substance

I don't think it is algal or fungal, I think it is a precipitate and possibly polyphosphate ?

I suspect Potassium Nitrate would be the candidate.

Unlikely, salts of monovalent ions are <"nearly all soluble">, so it doesn't matter what the K+ and NO3- ions encounter, that compound would be soluble. Potassium polyphosphate might be an option? at @X3NiTH might know?

and stuff falling out of solution after about 1 week or less.

Personally I'd half the strength of your mix

Same for me.

cheers Darrel

 

[Zeus.]

Is your dosing bottle in a dark place? You could also just double the distilled water and double the dose and see if that resolves the issue.


The K2SO4 is at the highest of the solubility limits. You could also just front load the K2SO4 direct into tank after WC.
I used a 'goal seek; in excel on KNO3 weekly ppm to work out your daily dose and the ppm figures you for the other salts don't all match the IFC results - but not a million miles away all the same.
Adding E300 and E202 may also resolve the issue.

 

[dw1305]

Hi all,

Currently it's (85g) KNO3 , (60g) K2SO4 , (10g) KH2PO4 , (30g) MgSO4 into 1L distilled

• (a) Made up to 1000 mL? (so approx 200g slats and 800g H2O) or
• (b) added to 1000 mL (so approx 1200 mL solution)?.

It should be option (a), but either way I'd definitely 1/2 the salts amount, so either the same weights made up to 2 litres or 1/2 weight made up to one litre. I'd guess your problems will go away at that point.

It is not relevant to your macro problems, but I'm a bit confused by the KH - GH booster as well



Do you have hard tap water? It just seems a lot of added dKH?

cheers Darrel

 

[blairgerman]

Thanks so much guys for the great feedback. I'll see about a photo of the white substance, but @dw1305 , it's possibly not algal but fungal might be accurate. Upping the container volume is probably best, I stopped at 1L cuz my blender is 1L then mix goes into some pump bottles for other tanks and most in my doser. @dw1305 I am adding the salts to 1000ml, so probably 1.2L total. After my move i haven't replaced a curtain I have along the back of the stand and light is indeed leaking in. So yeah, tap has high 12gh and low kh - i was suspecting silicates cuz we had some back and forth about calcium from my florida limestone and i started adding CaCO3 and observing some gross improvement. I regret I can't reasonably prep 36gal w/c of rodi in my small condo. @John q is right too, half the mix, double dose, use ascorbic and sorbate. @Zeus. below is what I have been working off of from IFC:

 

[blairgerman]

the back and forth about my tap water and Ca, Kh etc:

IFC Aquarium Fertilizer Calculator

Hi Hanuman, I now have distilled water to use. That makes sense with the Calcium did I miss a warning in the excel document that said that Calcium shouldn't be dosed weekly? No, Calcium shouldn't be added to your fert bottle but instead dosed directly to your tank weekly if you are...

www.ukaps.org

 

[Zeus.]

Your using the 'potential elements/compounds' from the tap water, which I didn't allow for - hence I was unable to get all the ppms matching 😳😉

I stopped at 1L cuz my blender is 1L

Using the blender to mix may be introducing some contaminates, depending what else it is used for, plus the more containers you used/transfer the liquids in and out off the chances of contaminates increases. Its very hard/impossible to keep things sterile with DIY ferts IMO, which is one of the beauties of dosing dry salts.

 

[_Maq_]

I suspect Potassium Nitrate would be the candidate.

It depends on the source. Potassium nitrate is widely used in food processing. You can get such a KNO3 for cheap but impurities may be significant. (In my country, at least.)
Beside that, another problem sometimes occurs. I don't know why but sometimes the production process involves Ca(NO3)2. Calcium is then removed (precipitated and filtered) using oxalic acid. I've encountered KNO3 containing excess calcium as well as another one with oxalic acid. Beautiful crystals formed in stock solution, but it was indeed useless.

(10g) KH2PO4

Whenever you add phosphates into a blend, you're at risk of forming precipitates. The only safe solution is dosing phosphate separately. (Or being fluent in chemistry and possessing the necessary know-how.)

Acidifying the mix will increase solubility

Will it? 😵
I think it depends on the compound in question.

 

[John q]

Will it? 😵

Lol, I have no idea, hence the question marks.

 

[MichaelJ]

Lol, I have no idea, hence the question marks.

As @_Maq_ indicated the solubility of many compounds strongly depends on the acidity of the solution and as with everything, it comes down to the specifics of which compounds we are talking about. For instance the solubility of CaCO3 increases greatly at lower pH - increasing almost an order of magnitude from ~7 pH to ~6 pH.

Cheers,
Michael

 

[X3NiTH]

The highest likelihood here is a Phosphate compound precipitating out, concentrate solutions containing Magnesium and Phosphate compounds can form less soluble or insoluble precipitates depending on the pH of the solution.



If the source of KNO3 you have has any Ammonia present then there is a likely probability that what you are seeing is Struvite (MgNH4PO4*6H2O) formation which can have a dendritic structure as it’s forming, it may appear as fluffy or fibrous to they eye in volume which would not look dissimilar to a Fungal Growth or Filamentous Algal growth.



Struvite formation pH graph.



You can see that if you acidify your mixture beforehand below a pH of 6 then it should help ameliorate the issue greatly for Struvite formation if there is Ammonium present as an undeclared salt contaminant.

Echoing everyone else I would also recommend not making such a concentrated mixture and especially not close to the solubility limits for any of the salts as charge imbalance and waters need to be electrically neutral will ruin your day/solution.

🙂

 

[dw1305]

Hi all,

at @X3NiTH might know?

If the source of KNO3 you have has any Ammonia present then there is a likely probability that what you are seeing is Struvite (MgNH4PO4*6H2O) formation which can have a dendritic structure as it’s forming, it may appear as fluffy or fibrous to they eye in volume which would not look dissimilar to a Fungal Growth or Filamentous Algal growth.

Thank-you, <"struvite">, I just couldn't think of the right mineral (or thread). I remembered <"your zinc (Zn) thread"> and I knew it wasn't that, but I was pretty sure it was @X3NiTH.

cheers Darrel

 

[blairgerman]

Your using the 'potential elements/compounds' from the tap water, which I didn't allow for - hence I was unable to get all the ppms matching 😳😉



Using the blender to mix may be introducing some contaminates, depending what else it is used for, plus the more containers you used/transfer the liquids in and out off the chances of contaminates increases. Its very hard/impossible to keep things sterile with DIY ferts IMO, which is one of the beauties of dosing dry salts.

"Potential" elements / compounds is defiantly the problem. I'd really love to not be using tap water. Even if I knew what was in there, it would change often. I'm just grateful my new home hasn't got any ammonia in tap as I had up to .5 at the last place.
And yes, my ferts go through multiple graduated cylinders, pipets, vials, measuring cups, and of course the blender (no food goes in there at least) so the potential for contamination is high. I need to do better with this so I can move closer to you guy's level. Dry dosing... hmmm. Thanks so much @Zeus , you and Hanuman's calculator is such a amazing resource.

It depends on the source. Potassium nitrate is widely used in food processing. You can get such a KNO3 for cheap but impurities may be significant. (In my country, at least.)
Beside that, another problem sometimes occurs. I don't know why but sometimes the production process involves Ca(NO3)2. Calcium is then removed (precipitated and filtered) using oxalic acid. I've encountered KNO3 containing excess calcium as well as another one with oxalic acid. Beautiful crystals formed in stock solution, but it was indeed useless.

Whenever you add phosphates into a blend, you're at risk of forming precipitates. The only safe solution is dosing phosphate separately. (Or being fluent in chemistry and possessing the necessary know-how.)

Will it? 😵
I think it depends on the compound in question.

My KNO3 is fertilizer grade, defiantly not food grade, so this is good to know. For my ignorant experiment i'm going separate the phosphate per your comment. I need better practices otherwise, but i'm gonna remove the KH2PO4 for now. Thank you @_Maq_

As @_Maq_ indicated the solubility of many compounds strongly depends on the acidity of the solution and as with everything, it comes down to the specifics of which compounds we are talking about. For instance the solubility of CaCO3 increases greatly at lower pH - increasing almost an order of magnitude from ~7 pH to ~6 pH.

Cheers,
Michael

My tank is a cloud of CaCO3 till the ph hits 6.5, then clarifies so quickly. A striking change.

The highest likelihood here is a Phosphate compound precipitating out, concentrate solutions containing Magnesium and Phosphate compounds can form less soluble or insoluble precipitates depending on the pH of the solution.

View attachment 209833

If the source of KNO3 you have has any Ammonia present then there is a likely probability that what you are seeing is Struvite (MgNH4PO4*6H2O) formation which can have a dendritic structure as it’s forming, it may appear as fluffy or fibrous to they eye in volume which would not look dissimilar to a Fungal Growth or Filamentous Algal growth.

View attachment 209831

Struvite formation pH graph.

View attachment 209832

You can see that if you acidify your mixture beforehand below a pH of 6 then it should help ameliorate the issue greatly for Struvite formation if there is Ammonium present as an undeclared salt contaminant.

Echoing everyone else I would also recommend not making such a concentrated mixture and especially not close to the solubility limits for any of the salts as charge imbalance and waters need to be electrically neutral will ruin your day/solution.

🙂

Wow, I can't wait to get a picture of the substance when it forms again. I need to get another microscope. This is defiantly the best fitting description of the substance. According to the data here, ph6.5 and below may be a good target, the possible solid phases percipitating posts you did are super helpful as well as the data provided here. Thanks so much for this and your other help for me.

@_Maq_ @Zeus. @dw1305 @X3NiTH @MichaelJ I have a clear plan of action now and I'm so humbled by the support and feedback i've gotten here. I made more progress during my year here at UKAPS than I did over many years elsewhere. Hope to get better with my quotes in responses.

 

[dw1305]

Hi all,

My tank is a cloud of CaCO3 till the ph hits 6.5, then clarifies so quickly. A striking change.

That means that your <"tank water is saturated"> with calcium (Ca++) and bicarbonate ions (2HCO3-).

Calcium carbonate (CaCO3) solubility is dependent on pH (via the <"CO2 ~ Carbonate ~ pH equilibrium">), and this means that you have about 17dGH and 17dKH at ambient CO2 levels. <"Global Monitoring Laboratory - Carbon Cycle Greenhouse Gases">.

As pH decreases the solid CaCO3 eventually dissolves into Ca++ and CO2 / HCO3-. When the pH rises again (when you turn the CO2 off) the CaCO3 will <"precipitate back out">, initially forming "cloudy" water.

It is not relevant to your macro problems, but I'm a bit confused by the KH - GH booster as well

I would stop using it.

cheers Darrel

 

[blairgerman]

Hi all,

That means that your <"tank water is saturated"> with calcium (Ca++) and bicarbonate ions (2HCO3-).

Calcium carbonate (CaCO3) solubility is dependent on pH (via the <"CO2 ~ Carbonate ~ pH equilibrium">), and this means that you have about 17dGH and 17dKH at ambient CO2 levels. <"Global Monitoring Laboratory - Carbon Cycle Greenhouse Gases">.

As pH decreases the solid CaCO3 eventually dissolves into Ca++ and CO2 / HCO3-. When the pH rises again (when you turn the CO2 off) the CaCO3 will <"precipitate back out">, initially forming "cloudy" water.

I would stop using it.

cheers Darrel

let me make sure i follow up on this. i think i got confused with my remin process. basically it's 5g calcium carbonate, 5g magnesium carbonate, and 5g potassium bicarbonate which I have been mixing with 136 liters tap water in a premix bucket to achieve a target kh of 6 i am seeking for some breeding livestock. This is after some back and forth about not using sulfates or sodium. I then add the 136L remin'd premix into the tank.
... chat about sulfates and sodium.

 

[_Maq_]

it's 5g calcium carbonate, 5g magnesium carbonate, and 5g potassium bicarbonate

Of those three only potassium bicarbonate is well soluble upon common conditions. The other two - put into the water - will form a white cloud which will dissolve eventually. The speed of dissolution does not depend on pH as much as on free CO2 content. Actually, these carbonates do not dissolve but react with CO2 to form dissolved and invisible bicarbonates.

 

[blairgerman]

Of those three only potassium bicarbonate is well soluble upon common conditions. The other two - put into the water - will form a white cloud which will dissolve eventually. The speed of dissolution does not depend on pH as much as on free CO2 content. Actually, these carbonates do not dissolve but react with CO2 to form dissolved and invisible bicarbonates.

Good to know. I hope this is still an effective way to get the Ca in there. Possibly i need to re-visit my remin compounds.

 

[dw1305]

Hi all,

...let me make sure i follow up on this. i think i got confused with my remin process. basically it's 5g calcium carbonate, 5g magnesium carbonate, and 5g potassium bicarbonate which I have been mixing with 136 liters tap water in a premix bucket...

It is like @_Maq_ says, calcium and magnesium carbonate technically aren't soluble in water, but are soluble in weak acids. Pure H2O becomes an acid when CO2 dissolved into it, but the excess of H+ ions is rapidly mopped up by any HCO3- ions dissolved in the water. At 420 ppm atmospheric CO2, as soon as you have more than about 2dKH the pH rises to ~pH8.

I'll ignore calcium for the moment, but if you add a soluble carbonate (sodium or potassium) to water that is already saturated with HCO3- ions the least soluble carbonate, (CaCO3) will precipitate out. The solubility limit (at 20oC and 420 ppm CO2) is about 17dKH.

You can get more bicarbonate into solution by in lowering the temperature, or by adding more CO2.

You've had to add CO2 to the tank to the dissolve the non-soluble carbonates, this means that you didn't have 6 dKH in the tank but ~17dKH.

If the water isn't cloudy when the CO2 goes off? your water isn't fully saturated with dKH.

Cheers Darrel

 

[blairgerman]

Hi all,

It is like @_Maq_ says, calcium and magnesium carbonate technically aren't soluble in water, but are soluble in weak acids. Pure H2O becomes an acid when CO2 dissolved into it, but the excess of H+ ions is rapidly mopped up by any HCO3- ions dissolved in the water. At 420 ppm atmospheric CO2, as soon as you have more than about 2dKH the pH rises to ~pH8.

I'll ignore calcium for the moment, but if you add a soluble carbonate (sodium or potassium) to water that is already saturated with HCO3- ions the least soluble carbonate, (CaCO3) will precipitate out. The solubility limit (at 20oC and 420 ppm CO2) is about 17dKH.

You can get more bicarbonate into solution by in lowering the temperature, or by adding more CO2.

You've had to add CO2 to the tank to the dissolve the non-soluble carbonates, this means that you didn't have 6 dKH in the tank but ~17dKH.

If the water isn't cloudy when the CO2 goes off? your water isn't fully saturated with dKH.

Cheers Darrel

ahhhh okay, i see where i'm going wrong then. I was testing the premix at 6dkh but this was inaccurate cuz the CaCO3 had not gone into solution. And when I test tank water at 6dkh it's not offgassed. I appreciate you guys' patience with me, you know i'm a good bit below expert level here. This gives me a better understanding for sure, but it will take a bit for me to digest some things. Indeed the water is not cloudy after the CO2 goes off.