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PO4 uptake

Paul K. wrote:

> Thus, if you can detect any phosphorus in your tank water at all, the
> plants are probably well supplied and their tissue contents are likely
> to be well above the critical value.  If the phosphorus content of the
> water drops after you add phosphate, it could be due to the plants
> increasing their luxury consumption.  It does not mean that the plants
> were actually deficient.  Also, there may be other ways that phosphorus
> is removed from the water column, such as reacting with iron or calcium
> and precipitating out.

I have to agree with this, but with a caution.  Inexpensive test kits may
detect phosphate (sometimes quite a bit of phosphate) even when none is
present.  Before you depend on *any* phosphate test kit you need to make
sure that its results are realistic.  One of my tanks once had a severe
phosphate deficiency when my phosphate test kit was showing more than 3
ppm of phosphate.

Roger Miller