SWG Explosions? Startup Recommendations & Powertab questions

[Guy559]

Hi all,

Previous non-SWG pool experience but this will be my first time with a SWG. We're due to add salt next weekend as we pass the 28-day curing mark.

While reading up in the FAQs and forums, noticed a small number of posts discussing what was believed to be SWG or pipe explosions attributed to chlorine and/or hydrogen gas buildup. I'm using a Hayward OmniLogic system with a TCELLS340. While I don't see an interlock option for the SWG and main pump, I'd like to believe the automation software won't energize SWG without pump on (and flow switch closed). Accurate?

Also, since the concern seems to be a buildup or collection of combustible gasses in the system, wondering if I need to remove my chlorine tablet feeder. I notice that it's after the flow switch and SWG, so--if gases can buildup and this reportedly can cause an explosion if an ignition source occurs--then would the tablet feeder be ideally positioned to collect and build those gases up over time? I can turn off the water flow but I believe this simply takes away water from flowing over the tabs. Don't know if it would disconnect the stack from the flow below it. Don't think it does.

Should I remove the stack feeder?

 

[ajw22]

I'd like to believe the automation software won't energize SWG without pump on (and flow switch closed). Accurate?

Yes. Your Omni system will not run the SWG when the pump is not running as long as the Omni is controlling the pump.

Should I remove the stack feeder?

Yes. Not because of a risk of it accumulating hydrogen gas but because use of the tablet chlorinator will murder your heater over time.

 

[Jimrahbe]

Guy,

Tablet feeders in a SWCG pool are just not needed...

Thanks,

Jim R.

 

[Guy559]

Yes. Your Omni system will not run the SWG when the pump is not running as long as the Omni is controlling the pump.


Yes. Not because of a risk of it accumulating hydrogen gas but because use of the tablet chlorinator will murder your heater over time.

Okay, appreciate it. Stack is past heater and there’s a one way valve to prevent Backflow, so heater should be okay.

 

[Guy559]

Guy,

Tablet feeders in a SWCG pool are just not needed...

Thanks,

Jim R.

Thanks Jim. Yup, don’t need the stack once SWG is kicking unless I want supplemental chlorine and to up CYA at same time. As it is, since CYA is sitting around 45, I’m just using liquid chlorine until I add salt. I’ll reassess CYA once SWG stabilizes.

 

[pjt]

I'd like to believe the automation software won't energize SWG without pump on (and flow switch closed). Accurate?

Your system should be setup to only power the SWCG when the pump is operating. There is a secondary SWCG flow switch safety device that will inhibit your SWCG unless it senses proper flow.

wondering if I need to remove my chlorine tablet feeder

Yes. The acidic and highly chlorinated water produced by the tab feeder when the pump is off will damage your SWCG and heater. If you ever need to use trichlor tabs, put them in a floater.

BTW, great Knighthawks profile pic. DFW AA guy now?

 

[ajw22]

Thanks Jim. Yup, don’t need the stack once SWG is kicking unless I want supplemental chlorine and to up CYA at same time. As it is, since CYA is sitting around 45, I’m just using liquid chlorine until I add salt. I’ll reassess CYA once SWG stabilizes.

Those chrck valves do not orotect the heater.

The acid will will get the valve to leak. By the time you realize what is happening the heater is damaged.

 

[Guy559]

BTW, great Knighthawks profile pic. DFW AA guy now?

Was a Wildcat back in the day (when Knighthawks were sister squadron in CVW-7). Didn’t pursue airlines route. Doing consulting and investing instead.

 

[Guy559]

Received a Flowviz meter for system today which I retrofit into a Hayward check valve. Awesome piece of kit!

With salt addition only a week away, I’m upping my knowledge via TFP FAQs and forums. I read a great thread by Jim (and others) that discussed running pump 24/7 and varying SWG % to get the desired output. I’m planning to do the same, especially since my DIY solar install helps offset electricity usage onsite).

I’m running a Hayward TCELLS340 for a 31,700 gal pool. Based on the Pool Math app, if I want 3ppm chlorine generation for this size pool, I should set at 54%. If I want 5ppm, then it’s a whopping 90%.

First, since S-series cells aren’t represented, is T-15 best analogue? Second, it seems a 40k cell is the biggest Hayward gets. So, it seems a higher generation rate might be needed, especially during summer heat, since there’s just the one cell. Any best practices?

I mapped my pump % settings to flow rate using Flowviz. Interesting to see that at 40% and above, based on my pump and piping, I get an almost 1:1 percentage to flow rate amount (e.g. 50% pump speed = about 50gph). Realize flow rate doesn’t impact SWG generation but figured handy to have an idea of pump speeds and resulting flow.

 

[Jimrahbe]

Guy,

The cell's required flow rate in the manual is just a 'guess' on what your cell actually needs in your pool...

Once again, common sense out weights gimmickry...

I would suggest that you just adjust the rpm or flow down until your cell just reports low flow.. Then, slowly increase the pump speed/flow until the cell just reports good flow.. Add a 100 rpm/flow and call that the slowest speed you ever want to run.. It makes little sense to be running your pump if you are not making chlorine.

Did you see the damaged F-4 pic I sent you??

Thanks,

Jim R.

 

[Jimrahbe]

DFW AA guy now?

Guy,

I too had 'assumed' that you were with AA..

That is what assuming will do for ya!!

Jim R.

 

[Guy559]

Thanks Jim, all makes good sense. Had seen your advice elsewhere also, which is why I wanted to map out pump speed to gpm flow rate. 40gpm should be more than enough to trigger flow switch. At 230watts, I can make chlorine 24/7, turnover water 1.8x per day, and only pull about 5.5kW per day or, as you noted elsewhere, only about $25/month… awesome!

Yes, saw F-4 photo. Never pays to dance with trees while flying…

 

[Guy559]

I'm sold on pulling the CMP Powerclean Ultra out since it's no longer needed. Anyone know is the 2" unions are standard for PVC? Read elsewhere that Hayward uses a unique twist/threadcount on theirs which requires a Hayward-specific fitting.

To be specific, will need the two male 2" threaded fittings so I can replace Powerclean with a straight run of 2" PVC. Thanks!

 

[ajw22]

I'm sold on pulling the CMP Powerclean Ultra out since it's no longer needed. Anyone know is the 2" unions are standard for PVC? Read elsewhere that Hayward uses a unique twist/threadcount on theirs which requires a Hayward-specific fitting.

To be specific, will need the two male 2" threaded fittings so I can replace Powerclean with a straight run of 2" PVC. Thanks!

Cut out the unions and glue a piece of pipe in.

You are going to be doing some cutting and gkuing for the SWG install.

PVC Repair - Further Reading

www.troublefreepool.com

 

[Guy559]

Cut out the unions and glue a piece of pipe in.

You are going to be doing some cutting and gkuing for the SWG install.

PVC Repair - Further Reading

www.troublefreepool.com

Thanks. SWG already in and ready... Powertab was downstream and only intended for temporary use -- using tabs for pre-salt chlorination and to raise CYA on a new pool.

Hoping to find a 'dummy pipe' I can swap in to replace the Powertab, as the union is so close to other items (see photo at top) that it'd require a lot more PVC work to rebuild everything which isn't necessary at this stage.

Worse comes to worse, I can probably just invert the Powertab to flood it, ensuring gas doesn't build up inside.

 

[ajw22]

Gas building up in it is not a problem. Leave it be and don’t ever use it.

 

[Guy559]

Gas building up in it is not a problem. Leave it be and don’t ever use it.

Okay, sounds like a plan.

The engineer in my cringes at the "SWG explosion" posts. Either a) this is a real issue and mitigation should happen or b) Other issues besides the hydogen/chlorine gas buildups caused the catastrophic pipe failures.

 

[ajw22]

Okay, sounds like a plan.

The engineer in my cringes at the "SWG explosion" posts. Either a) this is a real issue and mitigation should happen or b) Other issues besides the hydogen/chlorine gas buildups caused the catastrophic pipe failures.

As long as the SWG never generates when the pump is off all is good.

With water flow the water will carry the hydrogen bubbles onto the pool.

With no water flow the hydrogen accumulates in the cell.

 

[ajw22]

Here is one report - Explosion near the SWG

And another - Help,, my pipe exploded !!!

And another Exploding Pool.

 

[Jimrahbe]

turnover water 1.8x per day

Guy,

Since you seem to be in the learning mode, we can talk about the "Turnover" rule...

It is an old myth, and just not true.. It keeps being repeated over and over, but there is no reason that you have to turnover x amount of pool water each day.

It does not hurt anything, but we have seen several cases where pool owners were running there pumps faster and longer just to get to some mythological turnover rate.

The myth comes from the mistaken idea that your filter is there to keep you from getting algae, and to do that you must run x amount of water through the filter each day.

The truth is that your filter's job is to just capture whatever falls into your pool and floats.. By the time your filters starts to capture any algae, it is already way too late...

Keeping your FC in the proper relationship with your CYA is the way to make sure you never get algae.. FC/CYA Levels

Thanks,

Jim R.