How to choose a variable-speed pool pump
Pump model names change every couple of years. The way you choose one does not. This is the checklist — work through it in order, and it will still be right when today’s models are discontinued.
Start with the number, not the shop. Our pump sizing calculator works out the flow your pool needs and what that means at your plumbing’s resistance. Bring that number to step 3 below.
The checklist
1. Work out the flow your pool actually needs
Take your pool volume in gallons and divide it by your turnover time in minutes. Most residential pools aim to turn the whole volume over once in about eight hours. Small pools are a special case: plumbing codes set a minimum filtration flow regardless of how little water you have, so a tiny pool still needs a pump that can reach it.
2. Estimate the resistance your plumbing puts up
This is total dynamic head, and it is the number most buyers skip. It is set by pipe diameter and run length, every elbow and fitting, your filter type and how dirty it is, a heater if you have one, and any water features. Older pools plumbed in 1½" pipe have markedly higher head than newer 2" installations — often enough to change which pump you should buy.
3. Read the performance curve, not the horsepower
This is the step that separates a good purchase from an expensive mistake. Horsepower is not a flow rating. What you need is the manufacturer's published performance curve: the flow that pump delivers at your head. A pump advertised at 80 GPM maximum may deliver far less against real plumbing, because that maximum is measured at low resistance.
If you cannot find a published curve for a model, treat that as the answer and choose a different pump.
4. Check the electrical supply and the plumbing fit
Confirm what voltage is actually available at your equipment pad, and whether the pump you are considering is 115V, 230V, or auto-sensing. Then check the physical fit: union spacing, port size and the height of the pump body. A drop-in replacement saves you a plumber; a near-miss costs you one.
5. Check controls — and skip the timer
A variable-speed pump runs its own schedule, and that schedule is the entire reason it saves money. If you have pool automation, confirm the pump can talk to it.
Do not add an external timer that cuts power to a variable-speed pump. It does not give the pump a schedule — the pump already has one — it interrupts it. That advice belongs to single-speed pumps, which have no controls of their own.
6. Confirm the model is current, and check the warranty channel
Before buying, open the manufacturer's own product page for that exact model. Pool equipment lines get discontinued regularly, and retail listings outlive them by years. A discontinued pump is not necessarily a bad buy — they are often discounted — but you should know that is the trade you are making, because parts and support get harder.
Then read the manufacturer's current warranty terms for that model. Coverage often differs between an authorised dealer and an online purchase, and the online version is commonly shorter and parts-only. On a purchase of this size, that difference is worth more than a small price saving.
Why we do not name specific pumps here
This page used to be a head-to-head between two named models. One of them was discontinued by its manufacturer while the page still recommended it. On a site that updates itself, a recommendation naming a model is a recommendation with an expiry date nobody sees pass — so we removed it rather than repeat the pattern with two newer names.
The checklist above is what a good salesperson would walk you through anyway, and it stays true. Take your flow figure from the sizing calculator and the head estimate it gives you, then compare candidates on their published curves.