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Re: Black algae? or maybe a deficiency

On Mon, 23 Aug 1999, Bob Ashcraft wrote:
> Roger, have you ever gotten a reading from the AP kit?  If so, have you
> simultaneously tested with the Wardley kit to determine the error factor?


I don't recall that in that tank I have ever gotten a reading from the AP
kit.  I think the same could be said for my other more brightly lit tanks.

The question did pique my curiosity, so I used both tests on another tank
where I expected the nitrate level to be higher.  It's a 38 gallon tank
with low light, slow-growing plants and no CO2.  I keep a couple
boisterous 12-year-old clown loaches in there, and feed them rather
heavily (they beg).

Both the AP kit and the Wardley kit read between 20 and 40 mg/l.  The
Wardley kit seemed to be pretty close to 20, while the AP kit showed
something close to 30.

The lowest non-zero reading in my color chart for the AP kit is at 20
mg/l. Maybe when the nitrate concentration drops much below 20 the kit
stops registering anything at all.  The lowest color on the Wardly chart
is 10 mg/l but it seems to register detections at levels below 10 mg/l.

Roger Miller