Parallel Pumps


Jun 18, 2020
I decided to keep my pool open this winter and now I'm researching how to make my setup a little more energy efficient. I have a 1.5 HP main pump and a booster pump for cleaning. I haven't used the booster pump since buying the house due to the fact we don't like leaving the cleaner in the pool. My main pump works fine and may last many more years, but I hate running it for freeze protection due to energy consumption. After some online research I'm hesitant to go the VS option due to electronic sensitivity to surges. (it storms a lot where I'm at) 2 speed pumps don't provide a ton of options plus I'd rather not upgrade my timers. I'm curious if given my current arrangement with dual pumps and timers if I could replace my booster pump with a parallel 3/4 HP pump. This would allow me to run the 1.5 HP main pump for shorter periods and on demand cleaning, while using the 3/4 HP pump for circulation and winterizing. Basically creating a 2 speed pump system with separate pumps. Our pool is low maintenance so year round slow circulation is something we could really benefit from. I'm just brainstorming if a simple single speed smaller pump and a few fittings would be a lower price option to either 1) a VS pump upgrade or 2) a dual speed pump upgrade that would require a timer modification.

My biggest question concerning this option is if running the smaller pump would keep enough flow through the larger pump to prevent freezing during winter? If flow through the main pump would be an issue while using the smaller pump, I could always valve the larger pump off for isolation and draining. My goal would be to use the smaller pump for slow circulation during the summer and have a thermostat run it during the winter for freeze protection. The larger pump would essentially just be there for summer cleaning and skimming.

My current setup works fine, I just hate moving so much water to keep the plumbing from freezing. I'm basically looking for the cheapest option to install a low speed circulation arrangement. Any feedback would be greatly appreciated.


TFP Expert
Bronze Supporter
In The Industry
Aug 10, 2017
Morris Cnty NJ
How cold does it get in ur part of TX? If the pool is a simple setup it would be easier to just winterize for a few months. Once u purchase plugs it will cost you nothing after that.


TFP Expert
LifeTime Supporter
May 3, 2007
Pleasanton, CA
Pool Size
Salt Water Generator
You can just downsize the impeller of your current pump to a 3/4 HP. You shouldn't need a 1 1/2 HP pump for anything unless you have a high flow rate water feature.


In The Industry
Jul 14, 2014
The booster pump is just that, a booster. It is not designed to self-prime so would be damaged if you run it alone. Putting a smaller impeller is an excellent idea but a better one is to go ahead and get "name brand" variable-speed pump. After next July that's all you'll be able to get anyway. They all have "freeze protection" built in. They usually turn on for about 30 minutes then off for the same until the air temp warms. They all start this process at about 36 - 38 degrees. If they waited until 32 it would be too late.