How long before can you drain a gunite pool if you are retiling the water line tile of a pool or doing an acid wash on the pool?

It can be drained indefinitely as long as you have some way to ensure pressure relief from ground water. I plaster pools for a living (8 yrs)and we also acid wash. All you need to do is open up the hydrostat plug in the floor (preferably in the deepest part of your pool, ie. the bowl by the drains). If you don't have these plugs, please don't leave empty to long as your pool could float from the ground. Even without these though you are still fine to do maintenance such as a quick acid wash.

Generally, one must wait at least a half an hour before you drain the pool.

Well, the question really seems to be asking is how long do you wait before starting to draining your pool before you start work on the tiles. And/or I want to acid wash a pool -- how long can I wait before I start to drain the pool?

Maybe the question should state: I want to drain my pool to work on the tiles at the tile line and then acid wash the plaster -- How long can I leave it empty and dry before I have without substantial problems?

It may be possible to go up to 4 to 7 days before the integrity of the plaster is compromised depending on location and weather. Extreme heat and sun are tough and non-forgiving on dry plaster.

k

From A Pool Contractor

You can drain a gunite pool any time after 30 days past completing the interior surface process. Once the concrete has cured for 30 days you can drain the pool for any work that it will need. The newer in age the plaster is, the more likely it will be to staining, especially at the waterline. There is concern for hydrostatic pressure to lift the pool out of the ground should you live in an area with a high water table. Remove the hydrostatic relief valve from the bottom of the main drain and discard. You will replace this with a new relief valve after the renovation.

On a day by day basis you will want to wash down the pool plaster. If you leave construction debris, mortar and slurry on the plaster you will cause staining and pitting. It is preferable to have the pool be dry for as little time as possible as the plaster finish is likely to begin crazing and possibly separating should it be exposed to extreme heat. Freezing temperatures are also very hard on the interior surface of the pool.

Because the pool plaster will be at risk during this renovation, it is very common to renovate the tile band and then replaster the interior surface of the pool both during the same renovation. This will ensure the plaster is perfect at the end of your project.