Don't know the specifics of your area or pond (what elements N-P-K are there or missing , three primary ingredients of nitrogen (N), phosphorus (P) and potassium/potash (K), often described as NPK fertilizers) but here is some info on the matter.


Potash (or carbonate of potash) is an impure form of Potassium carbonate (K2CO3) mixed with other potassium salts. Potash has been used since antiquity in the manufacture of glass and soap, and as a fertilizer. The name comes from the English words pot and ash, referring to its discovery in the water-soluble fraction of wood ash.

The term has become somewhat ambiguous due to the substitution in fertilizers of cheaper potassium salts such as potassium chloride (KCl) or potassium oxide (K2O), to which the same common name is now sometimes also applied. In addition, potassium hydroxide (KOH) is commonly called caustic potash, an additional source of confusion.

The element potassium derives its English name from potash. A number of chemical compounds containing potassium use the word potash in their traditional names:

Until the 20th century, potash was one of the most important industrial chemicals .... it was refined from the ashes of broadleaved trees.


Potash, or carbonate of potash, is in fact a mixture of potassium salt with impure form of potassium carbonate (K2CO3). In other words, it is the common term used for the fertiliser forms of the element potassium (K). The name has been derived from the collection water-soluble fraction of wood ash in metal pots when its beneficial fertiliser properties were first recognised many centuries ago.