I have a 200 amp service a 50amp breaker outside and a 50amp gfi inside it trips the breaker outside not the gfi that is close to the tub don't know why the watts are 1500@120 and 6000@240 it says that a 50amp is the biggest one I need. Do I need a solid ground from the tub to the outside box?help me please

i have a 200 amp service a 50amp breaker outside and a 50amp gfi inside it trips the breaker outside not the gfi that is close to the tub dont know why the watts are 1500@120 and 6000@240 it says that a 50amp is the biggest one i need. do i need a solid ground from the tub to the outside box?help me please
Have you tested the GFI. If it is not working properly then replace it. You need a solid ground from everything to everything.

I get from your description is the 50 amp GFI breaker at the main panel does not trip, and a standard 50 amp breaker at the tub does trip.

If so, then the outdoor breaker may be defective, or there is a loose connection on the Line or Load side of the breaker. A loose connection at a breaker will cause heat, and the heat will migrate into the breaker and cause the thermal trip unit to activate, giving a nuisance trip for no apparent reason.

The circuit feed the tub should be four wire, with the two hots, 1 neutral, and 1 equipment ground, from the panel to the green screw or lug at the tub control box. At the service disconnect at the tub, the neutral should be insulated and isolated from the equipment ground, and the equipment ground both from the panel and the tub should connect to a lug directly connect to the panel's metal box.