hi everyone i baught a sump with a hole on the side which im not using if i put a bulkhead and stick a pvc in it and close the pipe with an end cap will that work and if anyone else has any better ideas please lemme know
Yes that will work fine. Use a threaded bulkhead and put plenty of pipe tape on the PVC fitting that you screw into it so it forms a really tight seal and will never leak.
You can do what Jimmy stated, or depending on the type of sump whether glass (another piece of glass to cover then silicone) or acrylic (purchase a piece large enough to cover the hole and use weldon to adhere pieces together).