You seem to be testing for the important ones although water hardness (GH
?) is a wasted effort. It means nothing in SW
chemistry. Magnesium would be a better test but typically is not needed very often.
Optional test kits would be PO4
, iodine/date, Mg
and possibley silicates. These though are not "regular use" but can often be valuable in determining problems. If you have a good LFS
willing to do the occasional test I wouldn't bother buying them really. If not they might be considered. Of the 4, Mg
would be the more important in terms of reef chem.
As far as what brands; with NH3
you don't need to be that picky. It's only the sensitive chemistry ones that give actual numbered results that become important. The better brands in that regard are Salifert, Seachem and La Motte.