if you shop petsmart go to their webpage and you can get the master test kit for about $14, print the ad and take it to your local petsmart..they price match.
it's not the cheapest but it will work out to be cheap in the long run as it provided many tests and does ph,ammonia,nitrites, nitrates
it's not the cheapest but it will work out to be cheap in the long run as it provided many tests and does ph,ammonia,nitrites, nitrates