Bulkheads

[Hez Yeux]

I was looking on Ebay for a tank and found one predrilled in the bottom for bulkheads. What are these? How do they work? How do they not leak?

 

[OrionGirl]

Bulkheads allow plumbing to pass through the glass. The plumbing connects to the bulkheads, either through threaded connections, or sealed slip fittings. The bulkhead has 2 pieces that thread together with the glass in between. Gaskets compress to make for a water tight fit. Holes can be capped if you won't be using them, as well.