Jacuzzi Salt Water Generator

[Sun_Devil]

I have been trying to fiddle with my SWG to get the correct run time.

I have a Jacuzzi J-SS40 system that is rated for a 40K pool. I have looked all over, and I can't find its daily output. Looking at similarly sized models on the Discount Salt Pool website, I estimated that it would be about 1.4 because those hovered around that amount.

Truth be told, I am not sure of my exact daily FC loss, but I would estimate that it would be between 3-4 ppm. Right now, every other day, I bump my FC from about 4.5 to 6.5 ppm before my SWG cycle (and based on my CYA my minimum is 4 ppm and preferred is 6 ppm). In short, I have to add liquid bleach every other day to raise the FC up about 2.0 ppm. My SWG is running at 60% for 12.75 hours. Given the numbers I have been using in the SWG calculator, the cell should be producing more than enough chlorine. Even if I bump the daily demand to 4.0 ppm and drop the daily output, I should have enough.

I know that I could start bumping up the output percentage, but this model only jumps in 20% increments. From my understanding, it is best to run it at a lower output power.

So, two questions (and a bonus)--

1. Where could I find the daily output of my SWG?
2. Does the pump speed mitigate the amount of chlorine produced? With a variable speed pump, I dial the RPM down to keep the water moving and close the flow sensor. I assume it doesn't, but I want to cover all the variables.
3. BONUS - Is it better to run the SWG longer at a lower output or shorter at a higher output?

 

[mknauss]

If rated for 40K it has to produce at least 1.4# per day.

The pump speed must be enough to close the flow switch. Be sure of that. Many times a dirty filter or a nasceant algae bloom can make it look like the SWCG is not producing.

The SWCG could care less if it is at 100% or 60%. So up to you on what combination of pump run time and % setting you use.

Do a Overnight Chlorine Loss Test to rule out algae. I assume you have tested CYA recently. It does degrade with high water temperature which we have in the summer.

 

[jblizzle]

It does not matter what output level you run at.

But, if it is working like it should, I too would think it was producing enough.

I would suggest raising the FC up to about 10ppm and performing the Overnight Chlorine Loss Test to see if something in the water is consuming the FC that the SWG is making.

Your questions:
1. Found this which says 1.32 pounds / day : Jacuzzi SWG That would be 13ppm in a day for your pool size. And your current output would be over 4ppm (which is certainly on the high side of normal)
2. Speed does not matter as long as it is enough to close the flow switch
3. Does not matter. Cheaper to run your pump as little as possible, so that would point to higher SWG % output.

 

[Sun_Devil]

Thanks for the information.

I will perform a OCLT tomorrow night. Too late tonight. I would be surprised if there was any algae. I have been militant about keeping the FC above the minimum. I test the chlorine at the end of the day, adjust with LC if necessary, and the SWG runs all night. The water has never looked more clear, and I have gotten compliments on it recently. Hopefully, the test will prove this.

I tested my CYA on Sunday. (I test it weekly.) The test shows between 70-80, but I could be wrong because I find that test difficult to perform. But, I repeat it several times, and most of my results fall in that range.

Stay tuned.

 

[Sun_Devil]

While I haven't done the OCLT, I have discovered some new information. This morning I went out, and the SWG's no flow sensor was tripped. For the last few hours, I have the pump running at 850 rpm. When I tested it before, this was enough to keep the flow sensor closed. The Jacuzzi cell is transparent, so I can see the hydrogen bubbles forming and see them flow out with the water movement. This morning the water level in the cell was about 1 inch below the top. And, there was a similar air collection in the filter basket area right before the pump. This doesn't happen at higher rpms.

At this point, it looks like all of my predicted calculations are off because I was assuming a longer run time. Now, I need to tackle this new issue.

So, my new questions--
1. Does 850 rpms seem too low? The amount of hydrogen bubbles produced does not seem like it is enough to create the collection of air that I saw while watching it work. I would think that it might be originating someplace else.
2. Given that I see the air pocket in the pump filter too, what advice do you have to find the origin of the air? Because my assumption is that even at low rpms, the system should be closed and air should not be introduced. It appears that the only reason I don't get that air at higher rpms is because it moves the air from the system quickly enough.

Thoughts?

 

[mknauss]

Sounds like you may have a combination of too low of a pump rate and possibly a DE filter getting clogged.

Try running your pump no lower than 1000-1200 rpm. VS pumps run at very low rpm are prone to build up of air in the pump basket and also are inefficient at those low rpms.

Always be sure to clean your filter when your pressure rises by 25% above your clean pressure.

 

[Sun_Devil]

At what speed to do you measure for the 25% rise? I would assume that you should note the pressure when it is running at the highest speed used during the pump cycle. The lower speeds barely measure on the pressure valve.

My filter pressure gauge has two arrows, and I have always been told to backwash when the pressure hits the other arrow. There is a difference of 10 PSI. At the highest speed after a fresh backwash, the filter runs at about 20 PSI. So, I would backwash after a 4 PSI increase?

 

[mknauss]

You pick a speed to use to measure your clean pressure and then monitor for your 'dirty' pressure. I use 1600 rpm as that is the speed my SWCG needs to close the flow switch.

- - - Updated - - -

Do not follow the 10 psi rise thing. Way too much rise. Use 25%. So if clean is 20 psi, clean at 25 psi.

 

[ajw22]

Your cellulose fiber in your DE filter is adding to your flow problem.

You cant go strictly by PSI raise to decide when to backwash. If your flow slows you have a choice of backwashing or raising pump speed. Chances are raising pump speed will just put off backwashing for a little while.

 

[Sun_Devil]

I did the OCLT last night. Started at FC 8.0 ppm and ended with 7.0 ppm. However, we had a thunderstorm roll through the area in wee hours of the morning with wind, blowing dust, and an hour's worth of rain. I would guess that even though this is on the border of acceptable parameters, I would say that I passed the OCLT, correct?

 

[mknauss]

I would agree with that. I assume you ran your pump all night? Or at the minimum, ran it for 30 minutes prior to taking your morning sample of water to test?

 

[Sun_Devil]

I would agree with that. I assume you ran your pump all night? Or at the minimum, ran it for 30 minutes prior to taking your morning sample of water to test?

Yep, it was running all night, and during the time both samples were taken.