mindscape100 said:
I was also wondering with regards to calculating how much water is in the aquarium.... Do you work out the volume of the tank from the basic dimentions or do you subtract the amout due to the substrate. With my tank that could accound for about 30-40 litres Id imagine. Any thoughts.
Thanks guys
John
Guys,
KH2PO4 is KH2PO4. The references you see to K2O has nothing to do with the chemical formula of the supplied powder. I believe there are certain regulations related to selling fertilizers in that the content must be expressed in terms of a standard reference chemical. In the case of Phosphorus, the content is normally expressed in terms of "equivalent P2O5" and in the case of Potassium the content might be expressed in terms of "equivalent K2O".
It's also a possibility that these are the the original chemical quantities used to produce the KH2PO4. Phosphorous Pentoxide (P2O5) is described as a white, flammable, dangerous, and extremely hygroscopic solid which reacts with water violently to produce Phosphoric acid (H3PO4). Potassium Oxide (K2O) is described as a colorless, hygroscopic crystalline which reacts violently with water producing Potassium Hydroxide (KOH). Since we can dose this powder without any violent reactions, it's safe to assume that neither P2O5 or K2O is present in this powder. Since the combination of [acid + base] always yields a salt it seems a reasonable assumption that the salt KH2PO4 is the result of combining phosphoric acid with the base potassium hydroxide. The data shown on the Garden Direct page therefore is likely the relative quantities of original acid/base used in the production of this salt perhaps as required by law.
If you review the Seachem site for Flourish Phosphorus you will see a similar analysis using these two original chemicals=>http://www.seachem.com/products/product_pages/FlourishPhosphorus.html
The bottom line is this: Buy the Garden Direct KH2PO4 and dose per the instructions in the EI article and don't fret.
Traces are a slightly different story only because trace elements are a mixture of 5 or 6 items so every vendor has a different recipe. As stated the Garden Direct Trace mix is higher in Cu than the AE mix. Sechem Flourish is a different mixture than TPN. No big deal.
Cheers,