If your metering valve is after the float tank near the pump, everything will work the same as it does right now. Remove the float tank and install the plumbing from the big tank where the float tank was. Then put the float valve out of the float tank in the big tank. Now you have a great big float tank. The pump will pull the water out of the big tank without any modifications. Just make sure the hose you use from the tank to the pump is stiff suction hose or even radiator hose.