Trisodium phosphate and Calcium nitrate precipitates but goes back into solution with addition of ethanol

[Dr. Jim]

I'm hoping Randy or any chemist can help me with this.....

I want to make a solution similar to Brightwell's FaStart M which contains, PO4, NO3 and Carbon. My reason for making my own is because, according to my measurements, the concentrations in the Brightwell product are extremely low and also I can fine-tune the amounts of each to get the exact amounts I have been dosing daily ). If my calculations are correct, I mixed a gallon of solution so when I add 16.8 ml to a 200 gal system, the PO4 will rise by 0.03ppm, NO3 by 0.1 ppm and 2ml of 25% ethanol (Red Sea NO3 PO4 X) will be added.

To make the solution, I first dissolved Trisodium phosphate, then Calcium nitrate in the proper amount of water (3785ml - 459 ml; the 459 ml is the amount of 25% ethanol needed, added last to make 1 gallon). The phosphate and nitrate mixture resulted in a milky white, cloudy solution which I assume is a precipitate. But, when the ethanol was added, the solution became crystal clear again.

MY QUESTIONS:
1) Can I assume that since the final solution is clear I should be able to use the solution and get my calculated amounts of PO4, NO3 and carbon and no detrimental changes to the compounds occurred?
2) Of less importance and just out of curiosity, what caused the initial precipitate (from the PO4 and NO3 compounds) and why did ethanol cause them to go back into solution?

Thank you for helping!

 

[Dan_P]

I'm hoping Randy or any chemist can help me with this.....

I want to make a solution similar to Brightwell's FaStart M which contains, PO4, NO3 and Carbon. My reason for making my own is because, according to my measurements, the concentrations in the Brightwell product are extremely low and also I can fine-tune the amounts of each to get the exact amounts I have been dosing daily ). If my calculations are correct, I mixed a gallon of solution so when I add 16.8 ml to a 200 gal system, the PO4 will rise by 0.03ppm, NO3 by 0.1 ppm and 2ml of 25% ethanol (Red Sea NO3 PO4 X) will be added.

To make the solution, I first dissolved Trisodium phosphate, then Calcium nitrate in the proper amount of water (3785ml - 459 ml; the 459 ml is the amount of 25% ethanol needed, added last to make 1 gallon). The phosphate and nitrate mixture resulted in a milky white, cloudy solution which I assume is a precipitate. But, when the ethanol was added, the solution became crystal clear again.

MY QUESTIONS:
1) Can I assume that since the final solution is clear I should be able to use the solution and get my calculated amounts of PO4, NO3 and carbon and no detrimental changes to the compounds occurred?
2) Of less importance and just out of curiosity, what caused the initial precipitate (from the PO4 and NO3 compounds) and why did ethanol cause them to go back into solution?

Thank you for helping!

Trisodium phosphate is very basic. Calcium can be of precipitated at high pH. Another possibility is that calcium phosphate precipitated. This gives us one reason the commercial mixture is more dilute.

When you added the 25% alcohol, you added more water. I think that might have been enough to dissolve the precipitate. Ethanol is not a solvent for the salts you are working with.

 

[Randy Holmes-Farley]

I'm not surprised calcium phosphate and calcium hydroxide would precipitate, but I am very surprised that ethanol helps dissolve either one.

 

[Randy Holmes-Farley]

Oh, now I read it more carefully, it is the vinegar in NOPOX that lowered the pH and solubilized both.

 

[Dr. Jim]

So would this mean that as long as the solution is clear (after being cloudy) it should be OK to use without any changes in the original concentrations?
Thank you!

 

[Randy Holmes-Farley]

So would this mean that as long as the solution is clear (after being cloudy) it should be OK to use without any changes in the original concentrations?
Thank you!

Generally speaking, yes.