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First Batch of Liquid Macro Ferts

FishWorks

FishWorks

Member
Joined
18 Dec 2016
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Location
Philippines
Hi Guys,

I am about to mix my first batch of Liquid Macro Ferts.
Could I get some advice on how to make it more efficient or simpler?

In General, My mixing procedure below:
  1. Use a 1000mL clear bottle as container
  2. 980mL Distilled water mix with 20mL vinegar
  3. Add KH2PO4 (weight depending how much is needed per tank)
  4. Add KNO3 and KCL (weight depending how much is needed per tank)
  5. Add Potassium sorbate 1g
  6. Final Solution pH should be 5 or lower (might need to add more vinegar because KH2PO4 will increase the pH)

Thanks!
 
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Hi,

I already edited the opening post, trying to make the formulation better.
Please do help, I am not sure what I am doing.

Thanks Again!
 
Hi all,
FishWorks said:
  1. 980mL Distilled water mix with 20mL vinegar
Click to expand...
You need to make it up to 1000 mL (with DI) when the salts are already in solution, other wise you'll end up with a lot more than 1000 mL of solution.
FishWorks said:
  1. ..........Final Solution pH should be 5 or lower (might need to add more vinegar because KH2PO4 will increase the pH)
Click to expand...
You should be fine. The potassium dihydrogen phosphate (KH2PO4) will <"actually lower the pH"> (you've add two H+ ions). It is di-potassium hydrogen phosphate that raises pH (you've added two K+ ions). They are conjugated weak acid and weak base in the <"phosphate buffer system">.

phosphate_buffers.jpg


cheers Darrel
 
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dw1305 said:
You need to make it up to 1000 mL (with DI) when the salts are in solution, other wise you'll end up with a lot more than 1000 mL of solution.
Click to expand...
What I think you are saying is..
If I took 1000ml of Distilled water, and then mixed in the salt fertilizers, Result is I would end up with more than 1000ml of Solution?
 
dw1305 said:
Hi all,

Yes.

cheers Darrel
Click to expand...
I got a couple more questions though.

So its perfectly accepted to use Vinegar and Potassium Sorbate in my Macro Mix right?

Also, Its good to aim for PH 5 or below for the final solution?
 
Hi all,
FishWorks said:
So its perfectly accepted to use Vinegar and Potassium Sorbate in my Macro Mix right?

Also, Its good to aim for PH 5 or below for the final solution?
Click to expand...
You can add the vinegar (or any other weak acid), but you don't need it. All the salts of monovalent ions are all soluble, so you won't get any precipitates, unless you exceed the <"total solubility limit">. In that specific case the least soluble salt will come out of solution first.

large_solubility_rules_chart-mk-png-png-png-png.png

You definitely don't need the potassium sorbate, it is antimicrobial activity is enhanced at low pH, but you won't have any microbial activity, you don't have a carbon (C) source like EDTA etc.

cheers Darrel
 
dw1305 said:
Hi all,

You can add the vinegar (or any other weak acid), but you don't need it. All the salts of monovalent ions are all soluble, so you won't get any precipitates, unless you exceed the <"total solubility limit">. In that specific case the least soluble salt will come out of solution first.

View attachment 215340
You definitely don't need the potassium sorbate, it is antimicrobial activity is enhanced at low pH, but you won't have any microbial activity, you don't have a carbon (C) source like EDTA etc.

cheers Darrel
Click to expand...
Nice chart.

Can I aim for PH 5 or below for the final solution?
 
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Hi @dw1305

I mix up my macros with DI water but I’m about to run out of my premixed trace elements and want to mix up my own.

I’ve been donated some phosphoric acid from a hydroponics friend. I was considering using some with Fe EDTA or DTPA and DI water to keep it in solution. I would probably have a trace elements solution and an Fe solution dosed separately but both within the photoperiod when my CO2 drops the Ph.

Does this seems like a reasonable idea? I’m not a chemist and don’t pretend to understand the chemistry but I believe chelation of iron allows it to stay soluble at ph below 7. I don’t understand what happens once that solution ph goes above 7. Does the iron become insoluble?

Thanks.

EDIT: Have been looking at this product and wondering if I need to dose chelated iron separately? https://solufeed.com/media/d41efptp/tec-sodium-free.pdf
 
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