Fill pool or drain it? - Opened pool to unusually low water level - leak probable

[Sinkerz & Floatz]

Noticed water level dropped several feet between closing and the spring. Opened up the cover and added several inches of water to perform the bucket test. Water level in the pool is definitely lower than the bucket after a couple of days.

My question is: Do I need to fill the pool, slam and balance and then identify where the leak is (food coloring test) to see if I can patch it? Or should I drain it completely?
If I call a professional, what would they do in this case?

The liner is ~10 years so is due for a change in the coming years anyway.

 

[ajw22]

My question is: Do I need to fill the pool, slam and balance and then identify where the leak is (food coloring test) to see if I can patch it?

No reason to add chemicals into the water other than liquid chlorine to keep the water from becoming a swamp.

Or should I drain it completely?

No, that will ruin your liner and it will not be patchable. And your pool walls may collapse without water in the pool.

If I call a professional, what would they do in this case?

The level the water level in the pool stabilizes indicates around where the leak likey is.

Once you see the level the water level stabilizes add water to the pool and keep the water level up until you find the leak and get it patched.