If you are worried about filling and emptying the fluid content of your developing tank, then consider this alternative:
Use tanks that already has the liquid in them, and use lifters to transfer the reels from one tank to the next in darkness.
This completely eliminates the risk of uneven development due to pouring liquid into the tank.
Obviously you need more than one tank for this, and a different working method, but it is a better way of uniformly coating ALL of the film with chemistry within a split second.
Edit: Or what konical said above.