you do know that electrical devices DIE on power on ??
Its like with bulbs... have you ever seen bulb die while shining ??? NO they always die on power on.
So having your pump running 24/7 might make t last longer.
Yes I have. Several times. AC power has fluctuations that can cause filaments to fail during use.
Anyway to the problem.
As a DIY option I'm thinking some sort of relay based switching system. You'd use a wire from a Molex or something to switch on a 240v AC relay. Relays do consume a little power when not switched but I'm guessing that won't be much of an issue.
And for something to buy..
I have a relay based mains plug that switches on and off two other devices depending on whether my PC is running. I know it's relay based as there's an audible click a few seconds after shutdown and another on start up.
I got mine free from some power company trying to talk me into going with them.
Innovatek PumpControl-O-Matic is for automatically turning on and off a 230 PC water cooling pump.
Innovatek PumpControl-O-Matic is for automatically turning on and off the circulation pump of a CPU water cooling. This is a "switch" which makes the pump together and simultaneously with the computer on and off, and as a forgetting, or the unnecessary operation of the pump impossible. Innovatek PumpControl-O-Matic is easy to power the pump is looped and connected to the computer and is fully automated.
With the pump control various applications are possible. Thus, the pump from the main board and together with the computer on and off. Here lies the pump control to a fan connector on the motherboard - like a normal fan
In conjunction with the Fan-O-Matic PRO also a follow-up control of the pump is possible. In this case the pump runs on after switching off the computer for a certain time.