Pat,
1&1/2" returns to the base of the tank will work well, and cause the least flow and pressure drop from the ampmaster. Even if you decide to stay with the 3/4" returns through the base of the tank (overboring the holes is prolly impractical with the overflows supplied by the manufacturers), running 1&1/2" pipe to the base of the tank and using a reducer at the base will keep pressure/flow losses to a minimum. There is a flexible PVC available from Lowes that is used for spas and Hot tubs that will allow for sweeping turns and cause the least amount of pressure drop, and is MUCH easier to work with in closed spaces. If you are only making the holes in the floor for the return line and 1 hole for the drain, you might want to make the drain a 3" drain line with a muffled fitting at the top for the venting. If you go into the wall, it may be easier to run a vent stack to the attic.
In my new tank I ended up making a pair of additional returns up and over the sides into 2 manifolds for the lower levels of the tank in addition to the returns that enter the tank through the overflows. If you do this, make sure to add some cutoff valves for the flow and use true union connectors to install/remove these fittings. (I T'd them off the 1&1/2 inch manifold under the tank). With the Ampmaster 3000 I almost have too much flow into the tank to be covered by the factory drilled drains (180 Gal AGA) with durso's installed.
HTH, use the extra flow from the ampmaster to your advantage.
1&1/2" returns to the base of the tank will work well, and cause the least flow and pressure drop from the ampmaster. Even if you decide to stay with the 3/4" returns through the base of the tank (overboring the holes is prolly impractical with the overflows supplied by the manufacturers), running 1&1/2" pipe to the base of the tank and using a reducer at the base will keep pressure/flow losses to a minimum. There is a flexible PVC available from Lowes that is used for spas and Hot tubs that will allow for sweeping turns and cause the least amount of pressure drop, and is MUCH easier to work with in closed spaces. If you are only making the holes in the floor for the return line and 1 hole for the drain, you might want to make the drain a 3" drain line with a muffled fitting at the top for the venting. If you go into the wall, it may be easier to run a vent stack to the attic.
In my new tank I ended up making a pair of additional returns up and over the sides into 2 manifolds for the lower levels of the tank in addition to the returns that enter the tank through the overflows. If you do this, make sure to add some cutoff valves for the flow and use true union connectors to install/remove these fittings. (I T'd them off the 1&1/2 inch manifold under the tank). With the Ampmaster 3000 I almost have too much flow into the tank to be covered by the factory drilled drains (180 Gal AGA) with durso's installed.
HTH, use the extra flow from the ampmaster to your advantage.
