HotSpring Clean Cycle

[Reese]

...Take the filter away from them and they would make sense...the circ pump have a high failure rate and it is not the pumps fault but usually debris getting in them.

I'm not following.  Isn't one of the purposes of the filter to keep debris from reaching the pump?

For what it is worth, the circ pump filter is always the dirtiest of the the three when I clean my filters.  IMO it is doing most of the filtration work on my tub.

[tony]

On a Sundance 880, the circulation pump is the filtration pump.  There are no bypasses on it.  So far, at least at our shop, there have been no failures of the new circulation pump.

But...the new SD circ pumps are high flow and push more water than low speed on traditional two speed pumps.

[drewstar]

On my Caspain, I have a single, pleated filter.  I can't imagine the circ pump contributing significantly to the filtering, esp since the filter has a floating ring around it.   I assumed the majority of water reaching the circ pump on my tub was through the intakes inside the tub, bypasing the entire filter.  Have I assumed incorrectly?

[Chad]

My circ pump filters my water 24/7 through one of my filters.

[Vermonter]

 the filter has a floating ring around it.   I assumed the majority of water reaching the circ pump on my tub was through the intakes inside the tub, bypasing the entire filter.  

Hi drewstar,

What do you mean by the above - i.e. what is a floating ring?  And is your circ pump not fed by a dedicated line (tubing)?  

On my tub, the inlet to the circ pump has a single feed (flexible PVC clear tubing) that is 100% safeguarded by a single dedicated filter.   The circ pump runs 24/7 and if you use a flow rate of even 3 gpm, then the total volume filtered daily is in excess of 4000 gallons.  At 5 gpm, it is over 7000 gallons.  But it is all protected by a filter.  Does your Caspian circ pump run 24/7?

Sorry - I went to the Tiger River site to download an owner's manual, but didn't find a quick link to it...

Vermonter

[Jacuzzi Jim]

 Generally as a rule all circ pumps draw water thru a filter,I dont know of any that dont. And to say a circ pump doesnt filter water just doesnt hold water here.

 As mentioned on another post  Sundance went with a highflow circ pump to be able to draw sufficent water thru there micro clean filter and it also just happens to filter a chit load of water as does the Jacuzzi 400 collection of spa's which uses the same pump as the Sundance.

 Artesian did the same with there platinum class spa's.

[Spatech_tuo]

I assumed the majority of water reaching the circ pump on my tub was through the intakes inside the tub, bypasing the entire filter.  Have I assumed incorrectly?

Your circ pump will be tied to the filter only, no bypass. Your jet pump has a bypass. You have indeed been assuming incorrectly. I'll add this to the list!  

[BBoppin]

Mr. V
Sorry for the misunderstanding in my terminology. I wasn't referring to the mazzei injector specifically. I was referring to the physics of circulating in a closed system that as water circulates, any tributaries or plumbing that intersects with that circulation also gets pulled into the stream, then replaced from the other end. not as fast as the initial circulation but inevitably does.This is the venturi theory. Similar to ocean currents dragging outside items into their stream. remember nemo. Also one other idea that holds true. Bodies of water are always moving and agitating. Just by shear spinning of the earth. As long as the earth spins the water no matter where it is will churn. When the earth stops spinning. You won't have to worry about the water in the plumbing of jet pump two. Just some boring trivia learned over the years. How bout those Patriots.

[drewstar]

Your circ pump will be tied to the filter only, no bypass. Your jet pump has a bypass. You have indeed been assuming incorrectly. I'll add this to the list!  

Oh god....I didn't know someone was keeping score.   :-?


 

[Chas]

Brad,

The circ pump on your Grandee has a small bleed line plumbed into various parts of the two jet systems. It is there for several reasons - one is to keep hot water in all parts of the plumbing. It is fairly good at that. I often turn my jets on after settling in to soak a few minutes, and I don't get a lot of cold water when first hitting the jet button in the newer tubs. My 10-year old Grandee does it a bit more in one seat than the rest, so I know this system is not moving 100% of all the water in every part of every pipe all the time, but there is enough that I don't worry about water stagnating in the jets not serviced by the clean cycle.

Second reason the bleed system exists is to help bleed both jet pumps of air when refilling from a water change. This puts a good flow of water into the base of each of the jet pumps. One of the many side effects of that is that when you put the Dichlor into the filter area, even if you don't run the jets - which you should - you will still have a strong chlorine dose introduced into each jet system.

Another reason the bleed system ties it all together is so that as much water will drain out of the tub's systems -all of it's systems - as possible when draining. This is to help get more water out when doing a simple water change, but it is also to help with freeze prevention in cold climates.

Another reason the bleed system is there is to keep major chambers - such as the filter compartment and MotoMassage compartments - moving. In all recent model HS tubs there is an outlet from the bleed system in the filter compartment. Go put your hand over it when the tub is on, no jets running. You will feel a mini jet of water coming out into the filter compartment. That stirs the water in that compartment far more than the fact that the circ pump is drawing water through one filter.

The assumption made in a previous post about the circ pump not being the main source of filtration in a HS tub is correct: the fact that they have designed thousands of gallons of water to move every day is a good reason to draw that water through a filter, and the fact that the one constant filter does get dirty fastest attests to the fact that this system adds to the overall ease of ownership by helping to keep the water clean. But if you allow the water to cloud a bit, you can run one pump via the timed clean cycle and do more filtration in ten minutes than most other spas do in an hour. Run both pumps manually for ten minutes, and you will do more filtration than some tubs do in a two-hour cycle.

Having the circ pump also filter is sort of a baseline filtration, and the reason that filter loads first is obvious - you don't run the other filters as often because they aren't needed as often. In fact, I have read many people who ask why HS doesn't allow for a scheduled filtration run by one or both jet pumps, and my answer - keeping in mind I don't design these things - is that it works great the way it is. I don't want my jet pumps running on days that I'm not in the tub. I don't need them to run that day or those days, and I don't want to pay the electricity for them to run. And in my experience, the HS system works as well or better than any other spa I have owned, and as well or better than others I have seen in the field as well.

 8-)

[Bill_Stevenson]

This is an excellent thread, thanks!

Bill

[Chas]

No charge.

[Vermonter]

Second reason the bleed system exists is to help bleed both jet pumps of air when refilling from a water change. This puts a good flow of water into the base of each of the jet pumps. One of the many side effects of that is that when you put the Dichlor into the filter area, even if you don't run the jets - which you should - you will still have a strong chlorine dose introduced into each jet system.

Hi Chas,

Thank-you for the clarifications on the circ pump.  When I can get out in daylight, I'll check out a few things on the plumbing and then post back.

However, a few points / questions:

1)  Depending on where the exact point of injection of the circ pump is with respect to the jet pumps, I think (I don't know - one reason I want to take a closer look) that it is unlikely that you would get the flow going both directions "through" the jet pump.  Flow hydraulics dictate that the flow will (almost always) follow the path of least resistance.  Depending on setting of valves, jets, etc. as well as the exact location of the point of injection, I don't believe the whole jet system would get chlorinated (brominated, etc.).  If a line feeding a jet is "off", then the water wouldn't make it there.

If the point of injection is at the pump head, then I presume it would be on the suction side?  Otherwise, during jet pump operation, the higher pressure would potentially push water back from the jet pump to the circ pump (assuming no check valves in the small circ pump feed lines)?

2)  Even if the idle jet pump train receives a chlorine dose, the linear velocity (in feet-per-second) is going to be next to nothing (remember that nearly all your circ pump flow is going through the fitting in the bottom of the tub, so the gpm flow through the small bleed lines has to be very, very low - likely well less than 1 gpm).  In long ago posts on biofilm, I had mentioned that one of the critical components to not only remove an existing biofilm but to effectively prevent formation of a biofilm is to have a "scouring" effect on the interior of the pump train (lines, valves, pump heads, etc.).  This requires a linear velocity  of something in excess of 10 fps (I think the number is more like 10 - 30 fps, but I can't recall the exact spec).  Regardless, the slight "bleed" flow from the circ pump in the jet pump train would not provide this velocity in the main jet pump plumbing and therefore opens the door to the possibility of a biofilm formation.  If the chlorine concentration is strong enough, then this would hopefully be unlikely - but it is possible.  And, not all owners use a proper disinfectant dose, further compromising this scenario.

3)  If, for the sake of discussion, we assume that chlorine is reaching all of the idle jet pump train and all wetted surfaces of that train, I still can't see a reasonable argument for HS not having the clean cycle activate both jet pump trains.  You would only benefit from that - there are no disadvantages that I can think of.  If the "clean" cycle operated for 10 minutes and both jet pumps were running (with all valves and diverters open), you would be 100% certain that chlorine was not only distributed throughout all weted surfaces in a HS tub, but also that optimal linear velocities (scouring) would be achieved with that disinfectant pretty much ensuring you of a microbiologically safe tub.  

Do you know if HS has ever considered having both pumps be activated during the "clean" cycle?  If "yes" and if they decided against it, do you know why?

Thanks, again, for the information and I will take a close look at the "bleed" lines.

Best,

Vermonter

[hottubdan]

My guess regarding 1 pump vs. 2 with clean cycle is the marginal difference in operating costs.

I have also heard that studies show biofilm creation in plumbing is quite common; not so much as to create health issues, but it is there.  I had a customer who told me her daughter participated in a study that showed spas with ozone had less biofilm than those without.

All hearsay, but...

[Gomboman]

Vermonter, perhaps you could run a DOE for us some day using your HS Grandee comparing the bacterial output for the two scenarios.

A. Bacteria concentrations for a given time using the Clean cycle.
B. Bacteria concentrations for a given time using the both Jet Pumps.

Would this be a difficult experiment to perform?