There are a number of water test kits and strips on the market (including
King British 6 in 1 Water Test Strips)
that are available from most good pet shops. We recommend that you regularly test the pH, ammonia (NH4), nitrite (NO2), and
nitrate (NO3) levels and if possible, the dissolved oxygen (DO) level too. It is important that the ammonia and nitrite are
at a very low concentration, and that the pH is stable. The nitrate level is less critical because it is not dangerous to
fish unless at very high levels..