If you are this far into this leak detection guide but are still struggling to find the cause for your leak then another tip is to watch the water level in the pool. This is especially useful for if you have a large leak with a high rate of water loss. If you were to let the pool continue to leak does the water level stop at any point or does it continue to drop? Since you should not drain most pools you do not want to just let the water level drop indefinitely as this could cause damage. It might however be worthwhile to let the water level drop on its own and see if it stops at any particular point. While this may not be a good idea for all pools, since most likely the water will turn green while you have the pool shut down for an extended period, the water level can still be a strong indicator as to the location of a leak. If you have a pool that leaks very fast (a few inches per day) then I would try this method. For slower leaks I do not think this will be as effective.

There are times where the pool will sit dormant, such as the winter season, where the water level might drop without you being aware of it. If this happens you might take the cover off of your pool in the spring to discover that much of the water has drained out of your pool. If this is the situation that you have then the point at which the water stops dropping will be a huge indicator as to the leak location. If the water drops until it reaches the bottom of the skimmer mouth then you most likely have a skimmer leak. If the water stops half way up the return port then this indicates a leak in the return lines somewhere. Same with the light or any other peripheral items in your pool. If the water drains completely out of your pool then this is a clear indication that the main drain is suspect. If you have a structural leak such as a hole in your vinyl liner or a crack in your concrete if you have a concrete pool, then inspect the pool carefully along the water level and you will likely find the problem. While letting your pool drain until it stops it not something you can do in most cases, on the rare occasion where you can let the pool find its own water level you will most likely also find the origin of the leak.

Never let your pool drain all the way empty !