DIY Phosphate Dosing

[Borat]

Hi Borat, Randy,

I have decided to go the Mono Sodium phosphate route as you suggested, do I use the same calculator for mono sodium and the tri-sodum?

1.88g of mono sodium phosphate for 1000ml solution.

Would this still equal .01ppm phos per 100ltr tank volume when 1ml is dosed, or do i need to adjust the amount?

This is more a question for Randy (I am not a chemist - although I can figure things out if needed)..

I ended up buying "Tri-sodium phosphate dodecahydrate" from ebay shop of APC: cost £12.95 for 500g - postage included.

 

[Randy Holmes-Farley Verified Community Expert]

Yes, there are so many other variables that you can’t know or control, it is plenty close enough. Regardless, you may need to dose much more than 0.01 ppm to detect 0.01 ppm remaining after dosing.

 

[e34stx]

I have started to dose p04 as my ulr phosphorus tester reads 0. I have been dosing for a week and now reads 3 ppb. I have noticed my rocks are turning brown with algae. I use a soft brush to remove the algae easily. Should I continue to dose the po4 until I get around 0.05 phosphate or stop because of the brown algae? Thanks

 

[ChrisfromBrick]

so- I have a one gallon container. I am adding just under 2 grams of loudwolf trisodium phosphate to be able to dose .25 ppm per 100L of aquarium water?

 

[tbrown]

so- I have a one gallon container. I am adding just under 2 grams of loudwolf trisodium phosphate to be able to dose .25 ppm per 100L of aquarium water?

lol

I would say that 2 g/L is likely perfectly close enough since tank water volume is imprecise, a potentially large and unknown fraction will bind to rock and sand, and dosing is typically by trial and error. :)

I believe to mix the solution to NeoPhos strength, this is the ratio. Are you looking for a weaker solution?

 

[tbrown]

Phosphate is 58% (57.93 % ) of trisodium phosphate. 1.88 is the grams of TP you will need to achieve about 1090 mg/l PO4 in the solution (1.88x0.58=1.09)
So you need to dissolve 1.88 g of trisodium phosphate to form 1 liter solution with 1090mg/L PO4 in it.
Actually I doubt Randy would give this 1.88 grams because it is not very accurate if you want 1000 mg/l PO4 solution :)
If the TSP is pure and anhydrous it will be 1.726 grams TSP to 1 liter water to form 1000 mg/L solution
(1,726x0.5793= 999 mg/L)

But because food grade TSP is probably partially hydrated I would say there is no big deal to use 1.88 grams per liter

This

 

[ChrisfromBrick]

I believe to mix the solution to NeoPhos strength, this is the ratio. Are you looking for a weaker solution?

I want a solution that will yield 0.01 ppm of phosphate per1 mL (tank volume is about 200L)

So if I have 1 gallon (which is the volume that i want to use), how much TSP powder do I add to that to get those results?

 

[tbrown]

I want a solution that will yield 0.01 ppm of phosphate per1 mL (tank volume is about 200L)

So if I have 1 gallon (which is the volume that i want to use), how much TSP powder do I add to that to get those results?

2 mg/L gives a concentration that will raise 100 gallons of water approximately 0.012 ppm per the Brightwell directions.

So, you want half of that concentration if you want 1 mL for 200 L to raise 0.01 ppm.

1 g per L times 3.785 liters per gallon is 3.785 grams per gallon but since we rounded up from 1.88 g to 2 g it's actually closer to 3.5 grams per gallon to raise phosphate by approximately 0.01 ppm per 50 gallons.

I think I did my math right... And I think I read your question correctly? 1 mL of 3.5 grams TSP to 1 gallon raises phosphates in 50 gallons of water by 0.01 ppm. 7 grams per gallon raises the same tank volume by 0.02 ppm.

@Randy Holmes-Farley my math is right, yeah?

 

[Miami Reef]

I made a recipe for my newest article I released:

Sodium Phosphate Dibasic (Na₂HPO₄) Recipe:
Sodium phosphate dibasic (Na₂HPO₄) is 66.9% phosphate (PO₄³⁻) by weight.

0.02 ppm in 100 L = 2 mg of PO₄³⁻.
2 ÷ 0.669 = 2.99 mg of Na₂HPO₄.

To make a stock solution where 1 mL = 0.02 ppm in 100 L:

Dissolve 3 g of Sodium phosphate dibasic (Na₂HPO₄) in 1 L of freshwater.

Dose 1 mL per 100 L to raise PO₄ by 0.02 ppm.

Note: Monobasic, dibasic, and tribasic forms are interchangeable. Concentrations vary slightly but are functionally similar when accounting for rock adsorption.

The Complete Guide to Raising Nutrients

Raising nutrients isn’t always easy; for some systems, it can feel like an uphill battle: confusing, frustrating, and full of contradictory advice. It’s not always clear which products to use, what to dose, or which filtration methods to adjust or remove. Chronically low nutrients are...

www.reef2reef.com

 

[tbrown]

I made a recipe for my newest article I released:

Sodium Phosphate Dibasic (Na₂HPO₄) Recipe:
Sodium phosphate dibasic (Na₂HPO₄) is 66.9% phosphate (PO₄³⁻) by weight.

0.02 ppm in 100 L = 2 mg of PO₄³⁻.
2 ÷ 0.669 = 2.99 mg of Na₂HPO₄.

To make a stock solution where 1 mL = 0.02 ppm in 100 L:

Dissolve 3 g of Sodium phosphate dibasic (Na₂HPO₄) in 1 L of freshwater.

Dose 1 mL per 100 L to raise PO₄ by 0.02 ppm.

Note: Monobasic, dibasic, and tribasic forms are interchangeable. Concentrations vary slightly but are functionally similar when accounting for rock adsorption.

The Complete Guide to Raising Nutrients

Raising nutrients isn’t always easy; for some systems, it can feel like an uphill battle: confusing, frustrating, and full of contradictory advice. It’s not always clear which products to use, what to dose, or which filtration methods to adjust or remove. Chronically low nutrients are...

www.reef2reef.com

So for his question above, raising 200 mL by 0.01 he would use 3 grams of 67% sodium phosphate per liter? So 11.355 grams per gallon?

 

[tbrown]

How does that compare to using trisodium phosphate?

 

[Miami Reef]

So for his question above, raising 200 mL by 0.01 he would use 3 grams of 67% sodium phosphate per liter? So 11.355 grams per gallon?

Yes. This is correct.

Let me run through the other calculations for the other forms. It’s close enough, anyway.

 

[ChrisfromBrick]

I made a recipe for my newest article I released:

Sodium Phosphate Dibasic (Na₂HPO₄) Recipe:
Sodium phosphate dibasic (Na₂HPO₄) is 66.9% phosphate (PO₄³⁻) by weight.

0.02 ppm in 100 L = 2 mg of PO₄³⁻.
2 ÷ 0.669 = 2.99 mg of Na₂HPO₄.

To make a stock solution where 1 mL = 0.02 ppm in 100 L:

Dissolve 3 g of Sodium phosphate dibasic (Na₂HPO₄) in 1 L of freshwater.

Dose 1 mL per 100 L to raise PO₄ by 0.02 ppm.

Note: Monobasic, dibasic, and tribasic forms are interchangeable. Concentrations vary slightly but are functionally similar when accounting for rock adsorption.

The Complete Guide to Raising Nutrients

Raising nutrients isn’t always easy; for some systems, it can feel like an uphill battle: confusing, frustrating, and full of contradictory advice. It’s not always clear which products to use, what to dose, or which filtration methods to adjust or remove. Chronically low nutrients are...

www.reef2reef.com

thank you

 

[Miami Reef]

Trisodium is 57.9% phosphate by weight
0.01 x 200 = 2
2 /0.579 =3.454
3.454 x 3.7854=13.0748

So add 13.1g in 1 gallon.

Each mL will raise 200L by 0.01 ppm

 

[vollkomm]

It just adds some water into it, and so it less potent. You'd need to use 2.3 times as much of the product you mention.

Dear Randy,

I was only able to get tri-sodium phosphate 12-hydrate with the following purity data in my area. The seller said it was lab grade. My question is, can I safely use this purity product to raise phosphate, or should I leave it?

Appearance: almost white crystals
Assay: 98,18%
Solubility: passes test
Appearance of solution: clear liquid
Chloride: <0,05%
Sulfate: <0,02%
Iron (Fe): <0,002%
Heavy metals (Pb): <0,002%
Free alkali (NaOH): <3,0%

Thanks,
Joe

 

[Randy Holmes-Farley Verified Community Expert]

Yes, I’d use that. The “lab grade” is meaningless, but the heavy metals specification is very desirable.

 

[Miami Reef]

Good luck raising the PO4. :)

 

[vollkomm]

Dear Randy,

I was only able to get tri-sodium phosphate 12-hydrate with the following purity data in my area. The seller said it was lab grade. My question is, can I safely use this purity product to raise phosphate, or should I leave it?

Appearance: almost white crystals
Assay: 98,18%
Solubility: passes test
Appearance of solution: clear liquid
Chloride: <0,05%
Sulfate: <0,02%
Iron (Fe): <0,002%
Heavy metals (Pb): <0,002%
Free alkali (NaOH): <3,0%

Thanks,
Joe

Yes, I’d use that. The “lab grade” is meaningless, but the heavy metals specification is very desirable.

Thank you very much!

 

[Randy Holmes-Farley Verified Community Expert]

You’re welcome.

Happy Reefing. :)