Inexperienced pond owners may simply use a site test to evaluate the quality of their water, figuring that if it is clear it is OK. Well that is not necessarily true. Sure, as a pond owner you strive for supreme water clarity, but the only way to truly know how safe your pond is, is to test the water. There are many easy to use test kits on the market that allow you to simply dip a stick in a water and use a color coded guide to identify the certain variable in your water. In a pond there are 4 parameters that need to be monitored consistently to ensure your pond and fish stay healthy and those are pH, ammonia, nitrite and nitrate. There are test kits available that can test all of those at once or kits that test for each one individually. Our preference are the all in one kits. When testing for these variables, here is a guideline of what you want each of thsoe variable to be so that you know your pond is healthy.
pH: Your pond pH should be at or near 7.0 which is neutral. Slightly higher, upt to around 8.0 can be ok. The key is to watch for pH fluccuations.
Ammonia: Should be as close to zero as possible and never above .5 ppm
Nitrite: Should be as close to zero as possible and never above .25 ppm
Nitrate: Ideally should be between 50-100 ppm, but even higher can be OK as generally nitrate are harmless but can fuel algae outbreaks.
Under normal conditions, weekly testing is a good idea just to be sure everything is OK and to also quickly identify a problem should one arise.