I have an icecap kalk reactor that I'd like to drill for an in and out so I can plumb a pump to the side of it to make it a nilsen reactor like in the picture.
I'm guessing a step bit would work to drill it, but I don't know the best way to plumb and seal it.
@AVAST Marine sells fittings for this purpose. I would check out their site. They also have instructions on how to dril their diy products which may help you