which nitrate test to believe?

[crazycat]

i now have 2 brands of nitrate test kits.

the old kit that i've been using since the tank was set up is tetratest--it goes increments of 0, 12.5, 25, 50, 100.

my test results always hover between 12.5 and ~20ppm. today they read a clear 12.5ppm

i just got the ap test (for comparison) and my results are totally different. the ap test says my nitrate levels are 5ppm--which is too low for my tank.

which test should i believe? does anyone have any experience with which one is more accurate? i may have been underdosing nitrates, but i don't want to overdose them either. i'm certainly not getting any sign of nitrate deficiency.

what do i do?

 

[Jchillin]

From my experience, the AP test has never failed me. I've never used the Tetra kit but just the results chart alone gives me a problem. 0 to 12.5 is just a little to far for an accurate reading.

 

[Wizzard~Of~Ozz]

When using the AP test, make ure you shake the heck out of bottle 2 for 30 seconds after you add bottle 1, then add it right away or it will read very low.

 

[crazycat]

ok--good to know.

the tetratest has 3 bottles of reagent and a small vial of zinc that gets added. it always semmed more "scientific". that's why i've been using it. butif everyone says the ap one is fine, as long as i shake it--and i shake the actual reagent bottle before i add it?--then i'll continue with the ap test.

just added no3--hope i didn't overdose... 8O

 

[macman7010]

Honestly anything made by Tetra, including thier filters, are in my opinion not of the greatest quality. The best test on the market I think is the Red Sea Freshwater lab. I know red sea tests are very accurate and easy to use.

 

[Wizzard~Of~Ozz]

the tetratest has 3 bottles of reagent and a small vial of zinc that gets added. it

Yup, that would be the same as the old one I had, (different brand), and it turns different shades of pink. according to it, my nitrates were @ 0, picked up the AP one and found out my nitrates were off the charts (even after a 50% PWC)..

they are now reading a stable 10 (unless I dose nitrate)..

mine was made by Marine Enterprises,

 

[malkore]

I had a Hagen/nutrafin NO3 test like that Wiz...3 bottles. It never gave me very good results, but the AP kit has been consistent for me, and I've even compared it to a Seachem kit and got within 1ppm. Seachem's is a nitrogen kit, so you multiply the result by 4.4, so you get different ranges than the 0, 5, 10, 20 on the AP...hence why it might be a little more accurate to the ppm...but we don't need to be that precise really.
As long as you know its 5ppm and not 50ppm, you're good