We have had a few customers with Boatman this season. Due to the extra rains, they have been travelling further than usual. Unfortunately, chlorine doesn’t seem to bother them. They are not dangerous but do have small pincers and can give a nip that you will notice. They fly around at night looking for the reflection of water to make a new home.
There is no effective way to prevent these bugs, but a pool blanket will help stop them and using a non-copper based algaecide, that will change the surface tension of the pool will also assist in controlling their numbers.

Water Beetle — Pool Maintenance Experts in Alstoneville, NSW