+1 on the Saliferts, and for Bignose, I have done the testing, I used 3 sets of Saliferts from different baches, 3 sets of API kits from different batches and 3 sets of Nutrafin from different batches, the Saliferts came out on top every time, especially the nitrate test kits, whereby the reagents are dry powders, whereas the API and Nutrafin kits use liquid reagents, bottle number 2 is generally the bottle that contains the solutions that will separate, over the time, so unless you shake them really well you generally get inaccurate results, although it is inevitable that some of the solution will remain as sediment as I've found that it hardens over time. All of the kits were tested against electronic equipment, and known reference solutions.
Not sure about US pricing, but I've heard that Saliferts are pretty expensive over there, but here in the UK, you can get the Salifert kits you require (NH[sub]2[/sub], NO[sub]2[/sub][sup]-[/sup] and NO[sub]3[/sub][sup]-[/sup]) for about £16-18 in total, then you can use any PH indicator as most brands use a form of bromothyml blue, unless it is high range where by phenolsulfonphthalein is generally used.
