I have been working on some detergent formulations and some specifications call for "super triple phosphate". The problem is that the formulations generally require all the inputs to be water soluble and in my experiments with "super triple phosphate" purchased naively, it is not a soluble substance.

So, in other words, I have bought product advertised as "super triple phosphate" which is generally available as a fertilizer, and tried to use it and it does not work because it does not dissolve in water.

So, what is going on here? Some of the possibilities:

  1. The written formulations I am working from are simply incompetent BS that do not describe real working detergents
  2. There are different kinds of "super triple phosphate", some of which (fertilizer) are not water soluble and others of which are. In this case, I need to know what the soluble form is called so I can find it and order it.
  3. The "super triple phosphate" needs to be processed in some way to make it soluble
  • 2
    $\begingroup$ Could it be triple superphosphate $\ce{Ca(H2PO4)2}$ (TSP)? Looks like the manufacturer decided to distort the name. $\endgroup$
    – andselisk
    Jul 11, 2021 at 12:58
  • 1
    $\begingroup$ @andselisk Ah hah, that seems to be the explanation. Some of the formulations I am working from come from a non-English speaker, so apparently they just screwed up the order of words. $\endgroup$
    – Shaka Boom
    Jul 11, 2021 at 13:11
  • $\begingroup$ FMI, you can find the history and usage of the term "super" in this question and you'll find why it might create confusion. The term had been used since antiquity so there is no proper rationale but has become a staple term in agricultural fertilizers. $\endgroup$ Jul 12, 2021 at 8:34

2 Answers 2


Detergent formulations would avoid introducing calcium ions in washing machines or handwashing formulations, so calcium salts are a no-no. Calcium phosphate is a good plant fertilizer, because it slowly release phosphorous in the soil. This is most likely what you purchased-a slow release fertilizer.

On the other hand, sodium triphosphate was a popular additive in laundry detergents. Unfortunately, it is also called trisodium phosphate (TSP). This is water soluble. Regardless, phosphates are discouraged now because they promote algae growth in waters. Whoever wrote triple super phosphate in your formulations was confused by the nomenclature.


Not sure what super triple acid is; but super phosphoric acid was used in agriculture ( I do not readily find a listing on the net today). It was 107 % phosphate as I remember. Fully water soluble as custom liquid fertilizers were mixed using it ( by Amoco and no doubt others ). It was stored hot ( 200 F ) to make it more fluid at the individual fertilizer bulk plants. At ambient temperature it was the consistency of heavy syrup. I happen to have waded in about 8" of it to inspect rubber linings in storage tanks. It was shipped in insulated , 316 SS lined, rail cars. There were two types , a "furnace" grade which contained traces of all sorts of stuff like Fl ; I forget the other grade but it was more expensive so not used as much in fertilizers. Today I use TSP as fertilizer and for cleaning and had not noticed it to be very difficult to dissolve in water.


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