I use the interpet pond test chemical kit. Its been good so far. Easy to use and understand. It comes with 4 test tubes, enough tablets for 10 tests and instructions. You just fill the test tubes with pond water, drop in the tablets, shake and use the colour chart for the results. It also tells you what to do or buy if your results show a problem. The test is for PH level, Ammonia, Nitrite and Nitrite.
well it depends on how strong of stuff you want to use.
Ive had many customers who say the extract of baily straw dont work. I wouldnt use any kind of ammonia remover. and as far as the treatments (especialy the aquaruim stuff) i wouldnt go near them with a barge pole.