Jim K wrote:

I then purchased the Mardel test strips - the 5 in 1 and the ammonia. They
are very easy to use and the results are easy to read. And the take very
little room under my aquarium. They are more expensive, however, and I
don't know how accurate they are.

I find the pH, KH and GH are roughly approximate, good enough for my
needs. The nitrate and nitrite are good enough to show if these are
present, but I usually fall back on other test kits, particularly for the
nitrite. For nitrite I use TetraTest (I found the AP one to be less
accurate). I use the Tetra kit for KH as well, but the rest of my liquid
test kits are AP.

I usually only test established tanks every month or so. My tap water
parameters are fairly stable (aka liquid rock, heh) and I have African
cichlid tanks for the most part with crushed coral substrate, so tank
parameters like KH and pH are rather stable even though I do inject CO2.
So the strips aren't too expensive given my uses of them. They're also
safer than the liquid kits considering I have cats who haven't quite
learned that counters are off limit. I have most of the liquid kits for
new/re-setup tanks to monitor the ammonia and nitrite spikes. I also used
them to "calibrate", as it were, the accuracy of the dip strips which is
why I know they are good enough for my needs (I am not too concerned about
minor fluctuations).