error in spa overflow plumbing. Should I correct?

[salinda]

While reading the forums, I discovered that I have an error in my plumbing that is probably the cause of some minor problems I have had over the years. My spa return and bypass for spa overflow are plumbed after the swg. This results in the spa becoming overchlorinated and having a slightly higher ph than the pool. In the past, I have had some calcium precipitation in the form of flakes, mostly in the spa. This was probably the root cause. The plaster still feels okay.

The plumbing is a little tight around the return plumbing on the pad. What I can do is at least have a small bypass plumbed from prior to the swg over to the spajet loop, which is currently a dedicated closed loop with its own plumbing. I could plumb in a check valve along this same bypass line so the jet pump doesn't lose prime or drain back into the pool when the filter pump is off.

Is this important to do now that I've found it or should I leave well enough alone?

 

[mas985]

My SWG is also plumbed before the valve which switches between the pool and spa. I believe that this is normal and necessary. Otherwise, there would be no way to chlorinate the spa during use when the demand is very high.

With the higher temps in the spa, you generally want to have a higher chlorine level and a few bathers in such a small volume of water tend to use up chlorine very fast.

However, my controller allows for different SWG settings for the spa and pool modes. This way you can set the spa for higher CL levels but limit it as well so it doesn't get too high.

I don't think you should change your plumbing but you may want to look into how the controller is configured.

 

[salinda]

I don't have that capability on my controller. I was thinking that if I just pump the overflow before the swg but leave the return 3-way valve after the swg, then I will still allow chlorination through the swg when the spa is in use. My spa is not heated very often so I mostly have the spa filtered by using the overflow and treating the pool and spa as one vessel.

 

[mas985]

I'm not sure I fully understand your point. Overflow mode should not add that much chlorine to the spa since most of the chlorinated water ends up back in the pool. The little that stays behind, should only be less than 1 ppm higher than the pool.

 

[JasonLion]

The SWG manufacturers seem to disagree on where to put the SWG, before or after the spa return splits off. The issue with before is that when running in spa mode with the cell active can cause the chlorine level in the spa to shoot way way up. The issue with after is that extended usage in spa mode can use up the chlorine in the spa without any way to replace it while continuing to use the spa. Pentair says before, AutoPilot says after, Hayward suggests both though they also mention that before can over chlorinate the spa.

 

[salinda]

Mark,

As an example:
I am currently trying to lower my TA, which is very high after a refill with fill water that has high TA (210!).

I ran the spa jet pump and ran the spa in fill mode so that all the return water goes into the spa and all the suction is from the pool. The pool did get a little lower TA (dropped 20) and a little higher ph (7.3). The chlorine was around 4. At that point, I tested the spa for the heck of it. The ph was much higher (7.6), which makes sense because the aeration was mostly there, and the chlorine was outside the scale of the drop kit. I didn't do the dpd test that day, just the visual comparison. It was a much darker yellow than the pool water.

I only have 2 returns in my pool, so maybe with the overflow even partially open (the normal setup), my spa is ending with a higher percentage of the return water than in most pools.

 

[mas985]

If your chlorine for the pool is 4 ppm and after you run in spillover it is over 5 ppm (max test level), then that may be within the norm.

The LM2-40 puts out 40 g/hr of chlorine so for a 2 ppm rise, the flow rate of the pump needs to be 88 GPM.

If the pump is putting out only 44 GPM, then the chlorine rise would be 4 ppm.

So what you are seeing is probably within what would be expected. With a CYA of 80, your target CL should be about 4 ppm. However, a standard pool target is as high as 9 ppm so even if it gets to 15 ppm, I don't think it would cause a problem. Running in spillover mode may raise the CL level but probably not high enough to worry about it.

As for spa mode, you will have issue of rising CL levels as the pump runs. Since the controller does not allow for separate settings for the pool and spa, you don't have many options. If you bypass the SWG, then you will need to add chlorine manually to the spa when it is heavily used, if you don't bypass the SWG, then you are having to deal with high CL levels.

Another option would be to manually turn off the SWG when running the spa or add a kill switch to the flow switch so that you can turn off the SWG easily.

 

[salinda]

What I am considering is leaving the current spa return as is but adding another bypass for overflow that would be fed BEFORE the swg and abandoning the old bypass. This way, in normal operations, the pool water (hopefully with decent CL level) will be feeding through the spa in pool mode. In spa mode, the water will be going through the swg and I will still have to override the swg if I run the spa for any length of time.

The kill switch for the flow switch is an interesting idea. Has anyone done this before? I know the blue wire from the cell is the flow signal, so I am assuming I would place it there. If I could tie it to the spa mode from the Jandy somehow, that would be ideal.

Since my swg is going on 3 1/2 years old now, I can probably wait until the cell fails to make any changes. That way, if the salt cell is no longer available and I have to change to a new system, I can make the plumbing changes at the same time.

 

[mas985]

What I am considering is leaving the current spa return as is but adding another bypass for overflow that would be fed BEFORE the swg and abandoning the old bypass. This way, in normal operations, the pool water (hopefully with decent CL level) will be feeding through the spa in pool mode. In spa mode, the water will be going through the swg and I will still have to override the swg if I run the spa for any length of time.

I wouldn't bother with changing the bypass for overflow mode. If you add the kill switch for running in spa mode, then it would actually be benificial to have the spa in overflow mode get a little extra boost of CL since it will no longer be getting any CL in spa mode. Again, I don't think you are getting that much more CL in overflow mode, at least not nearly as much as you would in spa mode.

The kill switch for the flow switch is an interesting idea. Has anyone done this before? I know the blue wire from the cell is the flow signal, so I am assuming I would place it there. If I could tie it to the spa mode from the Jandy somehow, that would be ideal.

It shouldn't be that hard to do. You need to find where the flow switch is wired into the control board and remove one lead which goes to one terminal of the switch and the other switch terminal goes back to the control board. When open, it will tell the controller there is no flow and stop the SWG. When the switch is closed, it should operate as normal. If have an extra relay available in your controller, you could wire it to switch when the spa mode is engaged.

Since my swg is going on 3 1/2 years old now, I can probably wait until the cell fails to make any changes. That way, if the salt cell is no longer available and I have to change to a new system, I can make the plumbing changes at the same time.

I am probably not telling you anything you don't already know but next time you might want a cell/controller which can support a spa and set the chlorine levels for the pool and spa separately.

 

[salinda]

I am probably not telling you anything you don't already know but next time you might want a cell/controller which can support a spa and set the chlorine levels for the pool and spa separately.

I know I know. I was an early adopter and jumped on this piece of equipment before I even found PoolForum, let alone TFP. I'm not even sure that some of the swg's that allow different pool and spa modes were available back then. Nor do I know if they would work with my Jandy. I jumped on a good deal from Leslie's and I am not sorry. I have never had algae problems. You are right that a little elevated CL in the spa is good because it has some corners that are always shaded and used to be prone to algae. Now I know that, if this becomes a problem, I only have to open the overflow bypass a little extra to get the fc a little higher yet in the spa.