Spa Bypass Valve - What Exactly Is It For?

[SoCalGuy]

The plumbing of our pool and spa is somewhat similar to this:

Instead of "Spa Make-up" our valve is labeled "Spa Bypass" and instead of connecting to the Spa Return line, it has it's own line returning directly to the Spa.

As far as I can tell, it basically just shuts off return flow to the spa... which seems redundant since that's what the Pool Return/Spa Return valve does.

What am I missing?

 

[bdavis466]

It more than likely is a spa make up line that allows for chlorinating the spa during normal circulation.

By bypass it could imply that it is bypassing the pool/spa 3 way valve so in essence bypassing the spa jets via a typical pool style return in the spa. If that is the case, then it's a good thing since you are avoiding the aeration the jets would normally create while running the spillway

 

[SoCalGuy]

It more than likely is a spa make up line that allows for chlorinating the spa during normal circulation.

Thanks, I get it now.

Our chlorinator is on the "Pool Return" line. So without the "Spa Bypass", the spa wouldn't get chlorinated.

The "Spa Bypass" basically diverts some of the filtered, chlorinated return water to the spa when the pump is in normal "Pool Return" mode. That water spills over to the pool and goes back into circulation.

That said, wouldn't it make more sense to have the chlorinator in front of the "Pool Return/Spa Return" valve so it could also chlorinate in "Spa Return" mode?

 

[bdavis466]

If the chlorinator was prior to the pool/spa valve, you could be dumping excessive amounts of chlorine into the spa when it was in use. Most salt systems are plumbed as you described but also use an automation system to regulate the chlorine production dependent on being in the pool or spa mode.

 

[SoCalGuy]

Good to know, thanks!

 

[JoyfulNoise]

If the chlorinator was prior to the pool/spa valve, you could be dumping excessive amounts of chlorine into the spa when it was in use. Most salt systems are plumbed as you described but also use an automation system to regulate the chlorine production dependent on being in the pool or spa mode.

The Pentair EasyTouch system automatically runs the IntelliChlor at 1/20th of the pool side output power setting when the system is placed in SPA mode, eg, 80% output in POOL mode equals 4% output in SPA mode. This allows the SWG to be placed before the splitting return valves and eliminates the need for a spa bypass valve setup. But this does require valve automation for the suction and return side valves.


Sent from my iPhone using Tapatalk,16k gal SWG pool (All Pentair), QuadDE100 Filter, Taylor K-2006

 

[bdavis466]

The Pentair EasyTouch system automatically runs the IntelliChlor at 1/20th of the pool side output power setting when the system is placed in SPA mode, eg, 80% output in POOL mode equals 4% output in SPA mode. This allows the SWG to be placed before the splitting return valves and eliminates the need for a spa bypass valve setup. But this does require valve automation for the suction and return side valves.


Sent from my iPhone using Tapatalk,16k gal SWG pool (All Pentair), QuadDE100 Filter, Taylor K-2006

Correct, but he is using a puck feeder, not a SWG

 

[SoCalGuy]

Having read up on pool chemistry, and lived with our pool for 12 yrs now, I'm starting to understand why so-called "automatic" chlorinators aren't all they're cracked up to be.

I get that pucks can cause calcium build up and scaling. Aside from that, in our case, the spa is used much more frequently than the pool and by more people in a much more concentrated body of water.

Yet where the chlorinator is placed in the plumbing now, it delivers NO chlorine to the spa when in Spa Suction/Spa Return mode. And the spa only gets the same amount of chlorine as the pool at other times.

Seems counter-intuitive that having the chlorinator before the return split would cause a concern about "over-chlorinating" the spa.

 

[bdavis466]

Having read up on pool chemistry, and lived with our pool for 12 yrs now, I'm starting to understand why so-called "automatic" chlorinators aren't all they're cracked up to be.

The more you read around here, the more you will see the disadvantages of using pucks

I get that pucks can cause calcium build up and scaling. Aside from that, in our case, the spa is used much more frequently than the pool and by more people in a much more concentrated body of water.

Pucks do not add calcium and do not directly lead to scaling, you either either confusing calcium with CYA or you are thinking of Cal Hypo (which definitely adds calcium).

Yet where the chlorinator is placed in the plumbing now, it delivers NO chlorine to the spa when in Spa Suction/Spa Return mode. And the spa only gets the same amount of chlorine as the pool at other times.

Seems counter-intuitive that having the chlorinator before the return split would cause a concern about "over-chlorinating" the spa.

Your equipment is set up that way because chlorinating the spa while while the pool is being chlorinated is possible due to your spa bypass line. There would be nothing wrong with placing the chlorinator prior to the pool/spa return valve (many many pools are plumbed that way) and the chances of over chlorinating the spa are very small (if you have any amount of CYA in the water) since CYA significantly buffers the strength of chlorine.

If you haven't had any issues with your pool, you are extremely lucky or very on top of testing and balancing your water. Using pucks for 12 years would mean that your CYA level is sky high, or you drain and refill your pool very regularly.

Most pool builders and plumbers know very little about water chemistry and the industry as a whole has made no attempt to recognize the relationship between FC/CYA. I wouldn't be at all surprised to find that the way your chlorinator is installed is the way that Waterway recommended it.

You could always run the spa with the bypass line open as well to chlorinate the spa while in use but I don't really know how much chlorine you would get from the pucks in that time frame since they erode so slowly.

 

[SoCalGuy]

Thanks Brian.. must be luck because I'm definitely not on top of testing and balancing. I keep an eye on it, but am hardly an expert. In fact, here I am 12 yrs post-build still not 100% sure exactly what the function of the bypass even is.

Aside from an occasional algae bloom, the only real issue we have is the calcium build up from our rock-hard San Diego water - which I still haven't figured out how to control.

Just to make sure I understand, CYA has no effect on alkalinity or ph, just the effectiveness of chlorine, is that correct?

We do normally run the spa with the bypass open. But as mentioned, when the pump sucks from and returns to the spa, the chlorinator - which is connected to the pool return - is completely out of the loop. So it makes no difference how fast or slow the pucks erode. They don't even get wet.

 

[bdavis466]

Can you post a picture of your equipment pad?

The whole purpose of CYA is to prevent chlorine degradation from the UV rays from sunlight and also to buffer chlorine's strength.

Alkalinity is a buffer for pH. The higher the alkalinity, the more tendency and faster the pH will rise. Alkalinity is required to prevent a pH crash and also to saturate the water with bicarbonate to prevent erosion of the plaster surface by leaching calcium from the mix.

The only way to lower the calcium level is to drain pool water and replace it with water with a lower calcium concentration than to pool...a very common occurrence in the southwestern U.S. since we get so little annual rainfall. There are reverse osmosis systems that can lower CH but they can be expensive.

At this point you might as well post a full set of numbers if you are looking for further advice.

 

[SoCalGuy]

Thanks Brian.

Here's a pic of the main plumbing. The spa pump and water feature pump are separate. Can't really get them in the same shot without climbing a tree or getting on the roof.

I'll post test numbers tomorrow or over weekend. Appreciate the help and advice..View attachment 44048

 

[bdavis466]

I guess I didn't realize that you had a separate pump for the spa. That explains why your plumbing is set up in that manner and also makes sense as to why the bypass does nothing for chlorination when using the spa.

You would really benefit from a variable speed pump and could eliminate the spa pump all together.