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Re: PO4 uptake



> Subject: Phosphate Test Kit
> 
> I've been using a Seachem Phosphate Test Kit for about a year now. Before I
> started dosing KH2PO4, the phosphate level was so low (~ 0.1 mg/l) that I
> didn't think much about it.  But now, on Tom Barr's advice, I'm trying to
> keep the level at 0.5 mg/l.  And, lately, I've begun to doubt the results of
> the test.  This morning, I tested the reference solution that comes with the
> kit and, instead of getting the 1.0 mg/l I should have, I got about half
> that.

If your tank was "hungry" it will suck out a high amount in a few hours.
Some folks swear that their tank actually eats PO4. It's almost freaky.

> 
> So, my questions are: Do the reagents "expire" in as little as a year, or is
> this test kit inherently inaccurate?  If the latter, does anyone have an
> opinion on which of the more expensive Hach or Lamotte kits would be better?

I think so. Some folks may not feel they are getting 5-8 times the worth in
their kits though for the increase in cost. I'm not too certain what exactly
a good target level of PO4 really is...........
If you hit between .5ppm and 1.5ppm 2-3 times a week, I would not fret too
much about the residual level(iron and traces also, same thing).

NO3 and pH are the two reading that need to be good and accurate. I am not
sure that spending more on test kits beyond these two are really needed
unless you got the $ or have a more research type exploration in mind. Don't
get me wrong, the best kits are nice and I encourage using test kits and
seeing what happens with the nutrients over the course of dosing and water
change cycles. I've been happy with the more expensive kits personally. But
some cheapys will surprise you.

> Thanks.
> 
> John T. Fitch

Regards, 
Tom Barr