When I bought the house 10months ago, I noticed that the bottom bulkhead was leaking. Turns out the previous owner attempted to fix it by putting epoxy on it. Somehow, not sure even HOW he did it, but near that bottom bulkhead had a 2" crack on the tank, crack started from the bulkhead and went out about 2". So it was leaking from there, leaking very slowly, like dripping every second.
30psi on a tank like this, there was no way in heck I was turning on the pump and risking it basically getting larger or worse just exploding (like say when Im at work or out of town). I contemplated changing to DE filter but cost was high as I would have to replace the entire tank. So I got a tank bottom for $300. Was hoping that it would be the exact same so didnt have to do replumbing either. And what happens? I get the tank, Jandy updated it a tad, meaning like the picture you show, inlet/outlet bulkheads are on the same side, exactly how my cracked one was. The new one they sent, inlet was on one side, outlet on opposite side. However it had the lower bulkhead your picture shows, but it was blocked off/provisioned for it, but one couldve hole saw'ed it which I was going to do. But then I wouldve needed a 3" cap for the outlet on the opposite side, Jandy wanted a week to two to send it, so Im like screw it, I dont have that time. So just ended up having to replug the inlet and outlet.
Turns out it was better anyways because I ended up eliminated about 5-7 extra feet of piping after replumbing it.
Here was original setup, you can see the inlet into the tank is the bottom bulkhead, outlet the top bulkhead which was going to Pool Frog chlorinator/chemical distributor thing. So eliminated that thing too.
Here is what it looks like now, you can see how I turned it at an angle so the pump goes into the inlet bulkhead on the right of the tank. Then outlet bulkhead is on the left which makes a straight shot to the LX heater now. Basically the bulkheads are the same height, except just on opposite sides.
Dixit