Mi42 baby. I gives repeatable results. One weird thing about it is that if you don't wash the vials really well, and you take a test after a week the first result can be wildly wrong. subsequent test however are spot on. Maybe Sean can shed some light on that? Its almost like the reagent reacts with the dried reagent from a former test? OR it could be that I am not completely washing them. I dunno, I have been really happy with them.
I try to keep my numbers in the range that Suncrest does. < 10 nitrates and <.5 phosphates.
I loathe when people say "these are ideal numbers, but don't chase them". What is that supposed to mean?
To me, the observed levels in your tank are the net result of nutrient input, nutrient absorption through growth, and finally nutrient export. Because these are constantly evolving and changing in your aquarium, then they are prone to float around a little. This is exacerbated in tanks than say 1 year old as the biology is still catching up with your nutrient levels in the constant cycle of boom and bust as the oscillations in bacterial populations swing less and less as the approach an equilibrium.
So you have inputs which are relatively stable (fish food and coral food).
Your adsorption which is also relatively stable but is subject to lots of environmental variation. It is basically your coral and alage growth rates which are effected by temperature, total amount of light, alkalinity, flow, ..everything.
Now your exports.. which are typically microbial off gassing of nitrogen, water changes, running macro algae.
So if you have high levels of nutrients then you have to A. feed a lot less or ditch some fish or B. increase export.
The ways to increase nutrient export are A. more water changes (expensive) B. Increasing bacterial populations through adding carbon (either vodka, vinegar or biopellets) or C. more powerful macro algae lights.
If your nitrates are really up near 50, I would knock that down a little. Just my 2 cents.