We're slowly renovating our 90~100 year old house and when we get to the bathroom we intend to install a spa bath. Not a large spa/jacuzzi, just a bath. Most of those we've seen so far come with a pump that quite frankly leaves a lot to be desired. We want something that will massage our muscles, not something similar to a can of beans. At the same time we don't want to be blowing off the jets or pipework or having to choke the pump because it's too powerful.

Is there some information or a web site that can assist us in determining a suitable pump size for a given application?


2 Answers 2


Are you planning to build an entirely custom bath unit? Or modify an existing product?

Most jetted tub manufacturers I've come across explicitly require certain pumps and void warranties if third-party pumps are used. For example, American Standard brand has the following in their installation doc:

Do not make modifications to the whirlpool system or remove pump from factory mounting. This could adversely affect the safety and performance of the whirlpool and void the warranty

I'd check with the manufacturer first before going down this route. If they do support it, they could probably make appropriate recommendations.

  • 1
    The market here is quite different to what you may be used to. We are able to buy spa baths complete with pumps or separately. Some baths have pump rating ranges, some don't. We intend to but a pre-built bath and pump separately. All the pumps we've seen supplied with bath and pump packages are really wimpy. If the manufacturer specifies a range the supplied pump is always at the bottom of that range. However, the top of that range might be more powerful than we need, so we can't use that as a guide either. Commented Nov 5, 2010 at 22:18
  • @John Interesting! In that case, I'll defer to the gurus. =)
    – Mike B
    Commented Nov 5, 2010 at 23:06

Great question. This hot tubs and spa site seems to offer a lot of information on the types of hot tubs and spas technicalities you are asking.

It explains that while the jets shape the water flow as it enters the tub, the real power behind them comes from the pumps inside your hot tub. Smaller tubs may have only one pump, but the popular 6'-7' models usually have two pumps in the 3-5 horsepower range; larger tubs can have even more pumps.

It also mentioned that more pumps at higher power means increased energy costs, potentially more noise, and a higher purchase price.

Good luck with your search!



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