I replaced my heater element last night ('95 Cal Spa), I had the two big push valves closed but was still getting tons of water coming out, about 1/4 of water drained as I was changing the element. There is a 3rd line going between the two main valves that I assume was leaking out all the water. In the middle of that line there is what looks like a valve that turns it has an --> on the valve showing the direction of flow. I tried turning it but seems like it either doesnt turn or is it froze. Do they turn?

Those push/pull type valves are known for not functioning properly, especially on an older tub. There are rebuild kits for the inside gaskets available for most of them. The 'valve' with the arrow on it may just be a flow switch or a check valve and not any sort of shut-off valve that you could turn.

Those must just be flow directionals. I think I will get a shut off for that seperate line when I put some different gaskets on the element tube.