If the pool needs clearing up, then add the bleach several times daily. If the pool is clear and you're just talking about the maintenance dose, then it's best to add it in the evening, if you can--that way it has all night to sanitize water without consumption by the sun. I would wait an hour or so with the pump running to test for chlorine after adding bleach--just need to give it enough time to thoroughly mix in the water.

Janet