Can't get bulkheads apart to remove...?

I am trying to take my tank down and I can't get the PVC/bulkheads apart to remove them. My question is which part comes out normally? I can't remember if the bottom PVC coupling is threaded or sealed or if the PVC slides out from the black threaded bulkhead? I attached the pics so you can see where I'm at with them... I have tried a lot of ways to unscrew but they are not giving at all. If I don't get a solution I'm cutting them off.

If anyone has run into this or has some experience in this area suggestions are appreciated!! Thanks in advance for any replies!

 

It looks at though they could be sealed but it is hard to tell from the pics.

 

yeah I installed them and I did not seal them. I think the PVC just slides out the bottom of the bulk but I can't remember if it's threaded or not. I have a reef safe solution I bought for cleaning my light covers to remove mineral deposit... I sprayed that on but still not budging. I was mainly wondering if anyone knew of anything that would loosen it up or if I have to buy a pipe wrench or something.

 

The PVC isnt threaded, it would just slip into the Bulkhead fitting or be glued into it.
That bulkhead go through wood, the wood might have gotten wet and swelled up
and is pinching the bulkhead.

 

ok thanks for confirming it's a slip connection... at least I know it isn't threaded.

 

Those fittings are too big for the bulkhead's hole in the tank anyways, so it's not coming out without being cut, or having the PVC fitting shaved down quite a bit with a dremel.

 

I used the size PVC for the fittings... the top came out, I think it's just naturally sealed because of not being loosened/touched for over a year. I decided I'm just leaving them in, if I need to move the tank the whole top of my stand comes off so the tank will be attached to that... If I get rid of the tank I'll just cut them out. Thanks for the suggestions though but I'm considering myself beat on this one.

 

gentle tap with flathead screwdriver and hammer.GENTLE!!

 

I learned years ago to use only threaded bulkheads, after helping many friends move their systems and having to cut them apart with a hacksaw. Threaded unscrews easily so you can set the tank down flat without having to block it up to clear the protrusions.
Its also nice if you want to change or modify the plumbing arrangement in the future so you don't have to waste a bulkheadm pipe and fittings, just unscrew and reconfigure.

 

I very large hammer and one good double handed swing they will come right out lol jk