Water parameter and test strip questions...

sort of anyway.. I picked up some Mardel test strips today, they say for
salt and fresh.. The 5 in 1 tests for NO3 NO2 pH and total
alkalinity/buffering. I have been worried about my 10 gallon tank (the 55 is
perfect at the moment after testing) And I also got one for ammonia.. The
tests for the 10 show:

ZERO nitrites
ZERO ammonia
pH 8.0 to 8.4, not quite sure which color really matches but it's one of
those or in between

Alk/buffering.. hard to tell because pad comes out splotchy.. did that with
the other tank too, kind of a yellow strip in the center of the pad, outer
edges blue.. what could cause that? Maybe not getting it wet enough?

Nitrates in the small tank show up at 80ppm.. no fish in that tank.. a
handful of caluerpa, about a pound chunk of live rock.. lots of bristle
worms and the tiny little shrimp looking.. copepods or something. i throw in
about 2 flakes of food once a week.. and just remembered i put the filter
pad in yesterday to get rid of some gunk i stirred up.. could that have
caused a nitrate spike overnight? (took it out just now..)

SG is fraction above 1.022 after a top up this morning.. (needs to come up I
think)

I want to be able to use this tank for quarantine.. but this tank has killed
two snails and a chocolate chip star.. one other snail survived just fine
and is in the 55. I am reluctant to put anything else in it but have never
been able to find anything seriously wrong. Would high nitrates kill snails
and the star?

Teeb