DIY Macro Solution Problems

Donovan

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Good Day everyone!

I'm trying to make a Macro Soultion of the following

6.52 grams KNO3
2.87 grams KH2PO4
18.27 grams K2SO4
11.65 grams MGSO4
500ml distilled water

I've made a couple of batches trying to dissolve all the salts but once I add the K2SO4 each time It precipitates out of the solution and some of it settles at the bottom of the bottle.
I'm not sure what I'm doing wrong cause I'm following this recipe from someone else.
I would be really grateful if someone could please help me out.

Kind Regards
Donovan
 

Zeus.

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but once I add the K2SO4 each time It precipitates out of the solution and some of it settles at the bottom of the bottle.

Which IMO suggests the water your using is already has salts in it, I take it your not using RO water so try boiling eater first let it cool and decanter the water before using it or get some RO water

the solubility of KSO4 is 111.1grams per litre so you shouldn't be having this ppt
 

Donovan

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Hello Zeus. Thankyou so much for the reply.

I was first using tap water and figured maybe that was the problem but then I switched to distilled water and the problem still persists.

I checked the TDS of the distilled water I received and its showed me a reading of 1.
I've been at this for the past 1 month and I cannot seem to get this right:confused:

Regards
Donovan
 

Zeus.

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500ml distilled water

oops sorry missed that in initial reply :oops:

Well I normally add 60g of K2SO4 per litre of RO water and no problems with solubility with it, takes a little time to dissolve but it does. So initially I would look at the purity of the K2SO4 which your using.

Here a list of the solubilities of the salts your using which is 75% of their actual solubilities

1603126077056.png
 

Donovan

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Thanks for the reply.

Maybe I should try and get K2SO4 from a different supplier and then do the mixture again.
In the meantime can I filter out the sediments from the bottom and use the fertilizer? Would it change the values by too much?

Regards
Donovan
 

Donovan

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Hello,
I could dry dose as you say but alot of people have said it better to dose on a daily basis than just once a week(not sure if its true) and dosing day salts everyday would be quite annoying.
Also I like having a solution pre made cause it's much easier and looks alot quit better than having the dry salts kept there haha.

Regards
Donovan
 

papa_c

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Interesting that I have also experienced this, I now disolve k2so4 separately from all other salts and then mix the two solutions together and don't get the any precipitation.

Never found out what causes it and I was never near the solubility limits.
 

Basviola

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Hey papa_c

I use the same salts for my micro. Different supplier ofcourse. I can dissolve a lot more of the salts. So I would also suggest trying a different supplier.

Roughly calculated what you would add to 1000ml water to compare it with the macro recipe I am using right now.

Would be very grateful if you could tell me your plan/reasons for adding the salts in these amounts? Also your dosing volume?
Trying to understand all this DIY fert dosing...

Your recipe
13 grams KNO3
5,7 grams KH2PO4
36,5 grams K2SO4
23 grams MGSO4
1000ml distilled water

My recipe
KNO3 62,8 g
KH2PO4 9,2 g
K2SO4 68,8 g
MgSO4 108,4 g
1000 ml boiled tap water
 

X3NiTH

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The precipitation you are seeing will likely be a variant of Magnesium Phosphate. If there is ammonia contamination present in any of the salts whether it’s derived from ammonium phosphate or ammonium nitrate when it hits solution and there is magnesium sulphate in the receiving water there is a chance for precipitation of insoluble MAP (magnesium ammonium phosphate). You can try to acidify your water to a low pH using citric acid (half gram in a litre of water should be enough) to help mitigate the effect. Ensure full solubility of each salt in the bottle before adding the next salt to the mix, if you keep seeing precipitation then you have a contaminated batch of salts and you need to test to find the culprit.

Heres a solubility rules table -

AF998AD3-6566-4501-95FF-FD7068655C1E.jpeg


:)
 

Donovan

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Hello everyone.
Thanks for all the replies.
Like @papa_c spoke about dissolving it separately and then adding it to the solution, well I've done that aswell and I still get the precipitate. It only happens with the K2SO4. I've added all the other salts and the solution remains clear. But once the K2SO4 is added the solution becomes slightly milky and slightly frothy and maybe after a few mins it starts to precipitate and settle at the bottom.
I've just placed an order with a new supplier and I'm hoping the problem doesn't persists.
I was experimenting with a few other salts like K3PO4 and MGN03 and I've realized once you add the above two together the water gets completely milky.
@X3NiTH I think you are completely right. It could be a variant of Magnesium Phosphate.
I've also tried adding about half a gram of ascorbic acid to the water prior to adding the salts and it was all good until I put in the K2SO4. As @Zeus suggested I think it could be a problem with the salt.
I'm really new at this. Sorry if these replies are quite stupid.
I've had these plants tanks for about 8 months now and it's getting quite expensive to buy a bunch of premium fertilizers.

Regards
Donovan
 

Zeus.

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You can try to acidify your water to a low pH using citric acid (half gram in a litre of water should be enough) to help mitigate the effect.

I suppose adding Ascorbic acid (0.5g/l) and Potassium Sorbate (0.4g/l) to help prevent mold and reduce the interactions PO4 and Fe, could/is also helping the K2SO4 to dissolve also- might just try adding some of my K2SO4 to 500ml of RO water
 

Donovan

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Hello everyone!
While we're on the topic of fertilizer does any have an idea to make a micro solution from scratch.
I'm actually from India and alot of what we get here isnt the greatest.
Any replies would be really appreciated

Thank
Regards
Donovan
 

Zeus.

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While we're on the topic of fertilizer does any have an idea to make a micro solution from scratch.

Yes, myself and @Hanuman are working on a DIY fert calculator, with help and guidance from some of the experts here and the Barr Report, the DIY trace section is the next section we are working on. The Program is excel based and it basically works out all the yields from grams of salts or from target concentrations and jives the grams of what salts to add. You can compare your yields with commercial ferts, AOI and traces mixes
 

Donovan

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Hey guys.
Just thought I'd give an update. So I got another batch of K2SO4 for a different supplier and there seems to be no problem at all now. I've even doubled the dosage and the solution remains clear.
Thankyou everyone for the advice.
Ps - @Zeus. Eagerly waiting for the new calculator. 😁. Cant wait to try making a micro fert aswell.

Regards
Donovan
 

Donovan

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Hello again,
@Zeus. Have you ever tried using tri potassium phosphate instead of mono potassium phosphate.
I've used it to make an alternate solution but the water turns completely milky. Does this happen with you'll aswell?
If anyone has made a solution using the K3PO4 can you please help me out.

Regards
Donovan
 

Zeus.

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Hello again,
@Zeus. Have you ever tried using tri potassium phosphate instead of mono potassium phosphate.
I've used it to make an alternate solution but the water turns completely milky. Does this happen with you'll aswell?
If anyone has made a solution using the K3PO4 can you please help me out.

Regards
Donovan
No I haven't used it and we haven't added it to the range of salts you can use in the calculator, we went through all the possible salts that could be used and if it wasn't easily available to purchase we didn't add them. Seems strange that its gone milky as that suggests it hasn't completely dissolved and K3PO4 has a solubility of of 90g/100ml, where as KHPO4 has a solubility of 26g/100ml.
@X3NiTH my have the answer, however the simple answer my be that the salt you have may not be pure K3PO4 and the other salt 'X' which is present just isn't as soluble as the K3PO4 so salt 'X' results in a milky solution when the compound is added to water.
Where did you get you K3PO4 from ? as I didn't get any hits for sellers when I google it
 

Donovan

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Hey guys
@Zeus. I managed to get it from a friend who is one of the distributors of chemicals and he lives near me.
However I just want to confirm if you think it's better to use the K3PO4 or just stick to the KH2PO4.?
I will again try to procure it from another seller and try the formula again.
Because using K3PO4 reduces the amount of sulfur added with the K2SO4.
Again I'm really sorry if this is all simple to you all but I'm really new at all this😁.
Thanks for all the replies.
Regards
Donovan
 

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