Attached Spa - Spillover and Maintaining Water

bagelman5000

Member
May 29, 2020
15
Westchester, CA
I have an attached spa for my recently completed in-ground pebble surface pool. The pool is 15 x 30 and the spa is 7 x 7. The spa does not have its own skimmer or pump and relies on the valve settings to move water in and out as well as recirculate. I have a Jandy iAqualink system so I can program all of this on a schedule. I also have a SWG for the system.

The question is how often I should be running the spillover function (pumping pool water into the spa and letting the spa spill back into the pool) vs recirculating the spa water every day. As of right now, I run the pump for the pool 11 hours a day (6am - 5pm) at a low RPM. At 5:00 pm I run the spillover function on the spa for 30 min (with the chlorine at 80%) and then the recirculation of the spa for another 30 minutes (which the chlorine at 5%). So far it seems fine, but I am worried about over/under chlorinating the water in the spa. I have checked the Cl somewhat regularly and it sometimes differs by 1-2 ppm one way or the other. We have been using the spa somewhat frequently (when we do it is in recirculation mode) so it can be hard to figure out if I'm under or overdoing it also because of usage.

Any experience with the best way to manage this?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,434
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Our typical recommendation is to run the spillover function for 30 minutes or so twice a day. Even at low flow rates that should be sufficient to chlorinate the spa water.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
24,024
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
What is your CYA level?

If you maintain the TFP recommendation of CYA 70 your target FC is 5 and your water is safe up to FC of 28. That gives you plenty of headroom. Depending on your SWG % and spa gallons it would take quite a bit of time to get your FC over a safe level.

Running your spa on SPILLOVER once or twice a day to refresh the water is all that is needed. Running your spa on recirculate with no one using it does not accomplish anything. I run my spillover in the morning to get fresh chlorinated water int he spa for the day and sun and then in the mid-afternoon to replace the chlorine that may have been burnt off by the suns UV during the day.
 

bagelman5000

Member
May 29, 2020
15
Westchester, CA
What is your CYA level?

If you maintain the TFP recommendation of CYA 70 your target FC is 5 and your water is safe up to FC of 28. That gives you plenty of headroom. Depending on your SWG % and spa gallons it would take quite a bit of time to get your FC over a safe level.

Running your spa on SPILLOVER once or twice a day to refresh the water is all that is needed. Running your spa on recirculate with no one using it does not accomplish anything. I run my spillover in the morning to get fresh chlorinated water int he spa for the day and sun and then in the mid-afternoon to replace the chlorine that may have been burnt off by the suns UV during the day.
The CYA was around 70 (according to the pool guy who did the startup) when we added the salt about a month ago. I haven't checked it since but I assume it is around the same level.

Wow, I didn't realize that the FC could be as high as 28 and still be safe! Good to know so I can always err on the side of too much FC.

What do you typically set the SWG for when it is in spa only mode? My guy said to put it at 5% because it will be recirculating but wasn't sure if it should be higher.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
24,024
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Assuming your spa is 800 gallons running your Truclear at 5% will raise FC by 0.3 ppm.hour

I would actually like to add 1ppm/hour of FC to the spa to replace chlorine lost from the high water temperature and bather load. Running your SWG at 15% would give you around 1ppm/hour. And you run no risk of FC getting unsafe even with a few hours of the spa running.
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
20,947
Bedford, TX
B-man,

When you are in the Spa mode, the system "assumes" that you will be using the Spa.. You really don't want the SWCG to be generating the same amount of chlorine that it would if you were chlorinating the whole pool.. This is why the system allows you to set a different amount of chlorine production in the Pool mode vs. the Spa mode..

I agree with Allen that around 15% is about the right number, but.. it is up to you to measure the Spa chlorine level and adjust that 15% up or down so that it works with your set up.. I don't mean you have to adjust it every day, I mean just get a feel for what it needs to be when you get out of the Spa and just use the %..

Thanks,

Jim R.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
24,024
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
What test kit do you have?
 

bagelman5000

Member
May 29, 2020
15
Westchester, CA
What test kit do you have?
It is an OREC kit I got from the pool store before I discovered this forum. It has pH, FC/CC, Total Alkalinity, and Acid Demand. I plan on buying the Taylor Kit once these reagents are gone.

I haven't felt the need to get the upgrade kit yet as I've only ever used liquid Chlorine and the SWG so the CYA should not have moved all that much in the two months since we've had the pool.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
24,024
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
I don't think you have the FAS/DPD chlorine test that gives you more precise measurements.

You also need to test your calcium (CH).

 

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bagelman5000

Member
May 29, 2020
15
Westchester, CA
I don't think you have the FAS/DPD chlorine test that gives you more precise measurements.

You also need to test your calcium (CH).

Good call. I have test strips for Calcium that came with the equipment that I did once when we started up and again when we did the salt, but haven't checked it since. I'm sure the test kit's version is much more accurate.
 
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