Written by one of our very helpful members, Waste aka Ted. Thanks, Ted!

The bucket test is used to take evaporation out of the picture (mark the pools water level, fill a bucket with water and mark the bucket level and set it on a step - check the next day and see if the pool level has gone down more than the bucket level) - if the bucket looses less water than the pool, you've got a leak.

The next step is to do a 'static test'. Plug all the lines going into and out of the pool while doing the bucket test. If the pool looses more water than the bucket - the pool vessel is leaking, if they loose the same amount, you've got a leak in the plumbing.

If you have a leak in the plumbing, pressure test the lines to figure out which line is leaking. (there are ways to isolate which line is leaking but, I'll stop here for now - and be ready to answer any questions you have, when they arise)