Originally Posted by matt4x4
Tree stumps decompose over time, it will eventually cause a sink hole, the decaying process will likely slow down once the pool is up since less moisture will get to the tree stump (no direct rain anymore), but since teh stump is organic in nature, it WILL decompose eventually.
If you are planning on having this pool for 20-30 years, I would advise you have the stump removed, however, if 10 years is a good enough time span for the pool, the stump will likely not become an issue.
If you center the pool over the stump, maybe you will get a deep end over time! :)