[minipol]

so you have 2 options: use a black hole creator (Inverted Quantum Beam ) and forget about the system or use a nebulae creator (Nucleonic Thresher Torpedo) and place spy sats in there so you can monitor what happens in the system. In case of renewed enemy activity, send a small fleet in.
If you can afford it, black hole creators seem like a better sollution but nebulae creator are not so expensive so you can build more in less time. As always, it will depend on the situation.