Variable speed pumps require a minimum of 2 inch pool plumbing. On many older pools, the pool plumbing is 1 ½ inches. In these cases, we recommend the use of a high-performance Hayward TriStar pump. These pumps offer up to 70% savings on your pool energy costs. It is the most hydraulically efficient pool pump that provides superior flow and energy efficiency. This allows for stepping down in pump horsepower for even less energy consumption. The heavy-duty performance motor with dynamic airflow delivers cooler operation and added energy savings.