I have used them, the sw master kit does have some differences, but also some of the same down to the same part number as the fw kit. The ammonia test would never read lower than .25, ever, so as long as you go in knowing that, they are definitely functional, but not what i would recommend. Hanna is super nice, but cost prohibative especially up front when you are testing every day or 2. I would recommend salifert personally. They are reasonably priced and have always been plenty accurate for anything i was doing. If you decide down the road that there is a test or a few you would rather see a number for, because at that point you will have had experience enough to know what is important to you to get a 'precise' number for and what is close enough, then get them at that point.