Selecting a Pool Pump
Unlike a larger pool filter, a bigger pump is not always a good thing. Unless you have been advised by a pool professional or are otherwise certain that your existing pump was undersized, it would be wise to keep the same horsepower as you have now. However, more important than matching pump horsepower is matching pump flow rates. Different pool pumps produce different flow rates, even if they are the same horsepower. Flow rates that are too high can damage your filter and piping, and result in ineffective filtration. Check pump Flow Charts to be sure, if changing pump models.
If your existing pump has been good to you, it is easiest to replace with the exact same make/model and size of pump. The height and length will also the same, which makes the plumbing job much easier, and the wires will match up better. A different pump will usually require some adjustment to fit the pipes to the height of the front inlet and the length to the back discharge port. Dimensions of most pumps can be found on any specific pump’s product page, and some do match up.