Phosphate test

[Zero Nitrates]

Is the phosphate we test for the type of phosphate caused by fish poo or the type of phosphate that is already in the RO water before we add it to our tanks through water changes?

 

[Randy Holmes-Farley Verified Community Expert]

With a very few exceptions, test kits we use detect inorganic phosphate. That is the main form in tap water and excreted by fish. It does not detect organic phosphate, which are organic molecules with attached phosphate. These are present in solid fish poop, as well as bacteria (DNA, phospholipids, proteins, etc.) and otherwise dissolved in the water.

If you had a kit that detects organic phosphate, you'd know it because it is much more complicated and expensive. It essentially digests the organic P to inorganic P before testing.

 

[Zero Nitrates]

Thanks Randy.

 

[Randy Holmes-Farley Verified Community Expert]

You're welcome.

I gives lot more detail on phosphate types here:

http://www.reefedition.com/phosphate-in-the-reef-aquarium-by-randy-holmes-farley/