Filter on a booster pump - commercial application

[holden94]

Hello all,
In case I never introduced myself properly, I am a state public pool inspector. That's right...I'm the devil himself. Along with inspections, I also conduct design review for renovations and new construction. Like most pool inspectors, I don't have the opportunity to actually operate or build pools and spas (should be a prerequisite for this position).

I have a very conscientious chief engineer at a large condo association that is building a new 2,800 gallon 9' x 18' in-ground spa. Like many, he struggles with keeping their existing spa clean when it is under heavy use. He was wondering if it would be helpful to install a filter on the booster pump system for the new spa? I can't see any downsides to this given that the filter would have to be sized properly for the max speed of a pentair intelliflo-svrs. But that is why am consulting TFP, to see if there are consideration I am not thinking of. My only concern is water stagnation in the filter when it is not used for any prolonged period.
Your shared thoughts are appreciated.

 

[mas985]

It kind of depends on what you mean by

he struggles with keeping their existing spa clean when it is under heavy use

Sometimes people say this when the problem is really about the chemistry and not the filter. The filter only removes debris from the pool but if the water is cloudy, then is likely to be a chemistry issue. Spas are so small, that nearly any filter is capable remove debris. So the existing filter should be more than enough for the spa. However, a filter won't remove or kill algae.

Public spas are notorious for having chemistry issues. Often times, the FC is allowed to drop and then there can all sorts of problems. If the FC level is kept at the appropriate levels, then the filters can do there job without having to contend with algae blooms or worse.

 

[holden94]

I agree with everything you said and yes a properly constructed and operated spa should be adequate. My experience has been that, especially in condo settings in ski country, there is little supervision and enforcement with respect to max bather load and showering requirements. Although there is more to discuss (and happy to have that discussion), I don't want to get off topic. I am seeking insight, experiential knowledge....would there be any disadvantages to installing a filter on a booster pump?

 

[linen]

Does the current spa have any additional oxidation, such as ozone or uv? Supplemental oxidation is often required and a good idea for high use public spas/tubs.

I would avoid additional filtration on the booster circuit and just make sure the filter circuit is properly sized. As mas985 said, it should not be needed and may only cause problems.

Although we are primarily a private pool/tub forum, we do occasionally discuss public installations. You may want to point the engineer to this site and have him post his chemistry readings on the current spa (if it still exists).

 

[holden94]

Thanks linen and mas985 for both of your responses. Very much appreciated!

I have learned a lot over the years from TFP. It is a great resource and many topics overlap into commercial applications.
I have turned a lot of operators on to this site and they have benefited as well.

Thanks again.

 

[mas985]

Just to add to what Linen said. I was steering you away from a filter on the jet boosters because there are quite a number of issue with doing that. First, filters filter much better at lower flow rates and can allow debris to pass through the filter at higher flow rates. The spa jet circuit usually has very high flow rates so this could end up causing major problems. Also, a filter generally has a maximum flow rate and even the largest are about 150 GPM. So depending on the number of jets and the flow rate per jet in the spa, putting filters on the jet circuit might require multiple parallel filters which is not very cost effective. The filters will work much better at the lower flow rates of the circulation circuit so there is absolutely NO benefit in putting filters on the jet circuit.

However, if the issue is with small debris in the spa, then you could look at other types of filters that do a better job of filtering smaller debris such as DE. If the issue is with cloudy water, that is more than likely a problem with the chemistry which no filter can solve.