Do you see some water coming out of your pool pump’s lid? Leave it be, and definitely don’t go and over-tighten it.
I believe the largest reason people do this (we’re talking to the guys in the room here) is because we see that when the pump turns off, there is a small amount of water squirting from the lid of the pump. However, this does NOT mean that your pump is leaking. Take a closer look at the lid when you go and switch it on and you’ll see that the water is actually getting sucked back down. When the pump is switched off a little water squirts out because the lid releases. This really is 100% normal and isn’t anything to be concerned with at all. A small bit of water ends up squirting from it and then that’s it. Nothing else.
The issue here is that when you go and tighten it too much you do a couple things. First, you make it extremely hard to remove it in the future. Second, you can end up damaging the seal that is on the pump’s threaded outlet and inlet. What this ends up doing is causing a vacuum effect where the pool pump will begin to pull in some air, running at a much noisier and rougher level. Most folks tighten the lid more to correct the issue that they think they’re seeing, but instead just make everything so much worse! Once the threads get damaged in this way they’ll likely need to be re-plumbed.
For many of these types of tasks, just keep in mind that if you find yourself in need of a tool for leverage, you’re probably doing it too tight.
Lastly, your pool equipment’s o-rings are manufactured from rubber for a very specific reason. That reason is that they are supposed to have some elasticity. If you end up cranking down the lid you can squish them so badly that they can actually end up losing their elastic nature, which will make all of your equipment issues worse.