ive no idea about pumps and currents and stuff like that, but i'd liken this to upgrading a PC. whether its a processor upgrade or new motherboard, bigger hard drive or more RAM. all you do is create problems cos as you upgrade one item, the other items don't work well with it. i stopped adding bits to PC's a long time ago, now i just sell and buy a better one. maybe this is what you should do.
just a thought.
derek