Porsche Boxster 1999, reservoir coolant tank leaking

[Hodan]

Good morning guys
Porsche Boxster 1999
My reservoir coolant tank is leaking in the trunk, I can see the water coming down the plastic bottle. is it recommended to put K & W Chemical FiberLock in it? I checked the cap and no water come from it, there is crack maybe.
I bought one aftermarket for 69$ on eBay apprentely it's the same.. Do u think it safe to replace it by the aftermarket one?
Thanks guys

[geraintthomas]

I'm sure an aftermarket one will be fine.