Good evening Shi thouse.
The little problem you have there is called " efflorescence". It is the inherent salt in the pavers finding its way out.
It is a problem that is common to most clay brick products.
It is usually more common after dry periods but can happen at any time.
The only cure for it is time or a sealant. I would advise against the sealant around the pool as it could become slippery and dangerous. The sealant stops the moisture coming out of the paver and therefore the slat drying on top.
The best thing to do is regularly wet the pavers down and eventually it will cease. Can't give you a time it will depend on the paver, it's location in relation to the pool, how often it gets wet etc.
Don't worry about though it is not dangerous nor is it a fault and it will eventually go away.
Hope this helps.
ET.