Minimum Pump Gph for SWG Systems

[shoyru177177]

I'm brainstorming the idea of a SWG for a small steel-framed, vinyl liner 1718gal pool that is annoying to maintain chlorine daily. In an old post, I saw a someone mention to oversize SWG 2-3x the capacity of your pool, i'm presuming so that you can generally maintain your FC at a lower SWG percentage, giving you the ability to raise the percentage you are running at to adapt your FC to correct chemistry issues and not end up nearing 100% to get through daily UV chlorine loss and other chlorine crises.

The SWGs I have browsed on Amazon all claim to need pump flow rates with minimum gph requirements that relate to the capacity of the SWG. After reading some posts and doing some quick and lazy calculations for basic pool pump sizing, this 1718 gallon pool only "needs" a pump that can handle 143gph to cycle all of the pools water capacity twice a day if run nonstop 24 hours a day (which it does). This pool came with a 330 gph cartridge filter pump, which I understand is still generally very weak in the grand scheme of things such as large pools, but for a pool this size is seemingly already more than twice what it "needs".

I have heard mentions of the dangers of having oversized pool pumps in that the pressure running through the cartridge could be too high, thus damaging the filters or blasting particles through that should normally be caught in the filter media, etc.


So my questions are as follows:

1. What are the downsides of having a pump that is below minimum recommended gph for the SWG?

1a. Would below minimum gph actually damage anything in the SWG or is it just another manufacturer's recommendation that is not necessarily applied in the real world?​

1b. Is the flow requirement there so that generated chlorine doesnt over-concentrate within the SWG?​

2. Theoretically, if this 330gph filter cartridge pump needed to be upgraded to something more powerful in order to run an "oversized" SWG, would that be unfeasible due to the small capacity of the pool and result in poor filtration?


Here are two various sized SWGs I have been browsing on Amazon with some of their listed specs that sparked this line of questioning.

The two SWGs share the same product page as size options. I am looking at the out-of-stock 2200 gal and 7000 gal capacity.

https://www.amazon.com/Intex-Saltwater-Electrocatalytic-Oxidation-7000-Gallon/dp/B073S4XJGF/ref=sr_1_1

2200 gallon capacity SWG:
" For small round and rectangular pools up to 12’ and 2,200 gallons "
" Filtration pump flow rate required: 300-1,000 gal/h "
" Chlorine output: 2g/hr "

and the next size up

7000 gallon capacity SWG:
" Requires a pump with a flow Rate between 700 and 3000 GPH "

Thank you in advance to anyone who reads and or decides to offer me any insight in my concerns.

Not really sure if this post belongs in SWG or Pool pump sub forums... kind of makes use of both.

 

[setsailsoon]

1. What are the downsides of having a pump that is below minimum recommended gph for the SWG?

1a. Would below minimum gph actually damage anything in the SWG or is it just another manufacturer's recommendation that is not necessarily applied in the real world?
1b. Is the flow requirement there so that generated chlorine doesnt over-concentrate within the SWG?
2. Theoretically, if this 330gph filter cartridge pump needed to be upgraded to something more powerful in order to run an "oversized" SWG, would that be unfeasible due to the small capacity of the pool and result in poor filtration?

You need to maintain sufficient flow such that the swg powers down on a low flow switch. If you don't have this you lose one layer of protection to prevent a potentially catastrophic event where hydrogen builds up and can explode. I would never do anything that compromises this safety device.

There are several benefits to ordering 2x swg. All swg cells degrade over time. This will enable you to go longer before you have to replace the unit and incremental capacity is much cheaper than the cost of replacement. This is based on typical in ground pool sizes over about 5000 gal. For very small pool volumes the pricing may be different but you could easily check that yourself.

I hope this is helpful.

Chris

 

[ajw22]

I'm brainstorming the idea of a SWG for a small steel-framed, vinyl liner 1718gal pool

Tell us what model pool you have? What model pump and filter?

I saw a someone mention to oversize SWG 2-3x the capacity of your pool,

That is correct. Otherwise you will need to run your pump close to 24 hours a day to get sufficient chlorine.

The SWGs I have browsed on Amazon

Which SWGs are those?

all claim to need pump flow rates with minimum gph requirements that relate to the capacity of the SWG.

SWG flow rates have little to do with SWG capacity. The SWG flow rate needs to be sufficient to clear the hydrogen gas that is a byproduct of the generation.

After reading some posts and doing some quick and lazy calculations for basic pool pump sizing, this 1718 gallon pool only "needs" a pump that can handle 143gph to cycle all of the pools water capacity twice a day if run nonstop 24 hours a day (which it does).

Turnover is a myth. You never can achieve close to 100% pool water turnover and you don't need it for sanitation.

Determine Pump Run Time

To figure out how many hours you need to run your pump, you need to know how fast your pump works. You can find this here.

www.troublefreepool.com

This pool came with a 330 gph cartridge filter pump, which I understand is still generally very weak in the grand scheme of things such as large pools, but for a pool this size is seemingly already more than twice what it "needs".

330 gph is about 5 gpm. Your pool only needs whatever flow is sufficient for skimming and chlorination.

I have heard mentions of the dangers of having oversized pool pumps in that the pressure running through the cartridge could be too high, thus damaging the filters or blasting particles through that should normally be caught in the filter media, etc.

You didn't hear that here.

So my questions are as follows:

1. What are the downsides of having a pump that is below minimum recommended gph for the SWG?

1a. Would below minimum gph actually damage anything in the SWG or is it just another manufacturer's recommendation that is not necessarily applied in the real world?​

1b. Is the flow requirement there so that generated chlorine doesnt over-concentrate within the SWG?​

Either the flow is sufficient for the flow switch to engage and the cell generates chlorine or it does not.

SWG flow switches do not need much flow to engage.

2. Theoretically, if this 330gph filter cartridge pump needed to be upgraded to something more powerful in order to run an "oversized" SWG, would that be unfeasible due to the small capacity of the pool and result in poor filtration?

A larger capacity SWG does not require more flow then a smaller capacity SWG. SWG capacity is increased by adding plates or increasing the size of plates in the SWG.

If you have an Intex pump it should work with an Intex SWG.

Post pics of your pool equipment.

 

[shoyru177177]

...the unit and incremental capacity is much cheaper than the cost of replacement. This is based on typical in ground pool sizes over about 5000 gal. For very small pool volumes the pricing may be different but you could...

Thank you Chris! Your insight is very helpful indeed.

...Which SWGs are those?...

Thank you for replying in such depth, ajw22.

The 2200 gallon option and the 7000 gallon option SWGs are in the following Amazon link.
https://www.amazon.com/Intex-Saltwater-Electrocatalytic-Oxidation-7000-Gallon/dp/B073S4XJGF/ref=sr_1_1

The pool is the Bestway 56417 Steel Pro Above Ground, 12ft x 30 Inch in the following link.
https://www.amazon.com/gp/product/B01E1130DM/ref=ppx_yo_dt_b_asin_title_o00_s00

The included pump is the Flowclear 330 gal. Filter Pump as follows.
https://www.amazon.com/Bestway-58511E-Flowclear-Pool-Pump/dp/B07G344N5Q

Pictures of the actual pool are unlikely to be provided as I am researching and brainstorming in lieu of a friend who actually owns said pool.

------------

This pool does not contain a skimmer and its 330gph cartridge filter pump runs 24 hours a day as current.

Am I correct to infer from your comments that you do not generally believe an oversized pool pump is harmful in any way? Then perhaps this 330gph pump could be upgraded to lets say, a 750gph-1000gph pump to be in the clear for recommended flow rates for the 7000 gallon Intex SWG in the Amazon link?

The Intex SWGs I have previously linked (at least the 7000 gallon capacity one in particular) list that they do come with an assortment of adapters for both Intex and non-Intex pools, as well as other reviewers have reported success with compatibility with their Bestway pools as well.

The idea of a larger capacity SWG requiring more flow comes directly from the product listing in which they list varying minimum gph flow requirements per each different capacity SWG. From the information both you and Chris provided, I am guessing that the SWG product listing may be accounting for the flow switch when mentioning minimum gph flow rates, whether their numbers are overkill or not.

 

[ajw22]

This pool does not contain a skimmer and its 330gph cartridge filter pump runs 24 hours a day as current.

Let's talk about flows in gallons per minute (gpm) not gallons per hour (gph). The manufactures of this small pool equipment like to specify 330 gph because it sounds like a big number. If they said it as a 5 gpm pump people would realize how slow the water flow is. A kitchen faucet may flow at around 3 gpm.

Am I correct to infer from your comments that you do not generally believe an oversized pool pump is harmful in any way?

A pump can't be oversized. Although a large pump can put a flow into the pool that feels like a fire hose and you probably don't want that. And your suction port may nor be able to feed enough water to too large of a pump.

Then perhaps this 330gph pump could be upgraded to lets say, a 750gph-1000gph pump to be in the clear for recommended flow rates for the 7000 gallon Intex SWG in the Amazon link?

Get an Intex pump and filter like this that will pair with the Intex SWG....

https://www.amazon.com/Intex-28633EG-Krystal-Cartridge-110-120V/dp/B005QIYM6E/ref=psdc_1273007011_t3_B07G344N5Q?th=1

The Intex SWGs I have previously linked (at least the 7000 gallon capacity one in particular) list that they do come with an assortment of adapters for both Intex and non-Intex pools, as well as other reviewers have reported success with compatibility with their Bestway pools as well.

What I would do is get the Intex SWG and give it a try with the Flowclear pump/filter. Either it will be enough flow for the flow switch and it will work or it will not. If it works great and if not then upgrade to the Intex pump which has a larger filter.

The idea of a larger capacity SWG requiring more flow comes directly from the product listing in which they list varying minimum gph flow requirements per each different capacity SWG.

I don't put a lot of faith in manufactures specs and they are often written by the marketing people and not the engineers.

From the information both you and Chris provided, I am guessing that the SWG product listing may be accounting for the flow switch when mentioning minimum gph flow rates, whether their numbers are overkill or not.

I think it is more marketing then engineering specifications.

Be aware that these Intex SWGs typically last a few seasons at best. View them as a disposalble consumable device. They only generate at 100%. So you need to use your pump runtime to adjust the daily FC generation your pool needs. Running an oversize SWG with a pump running 24/7 will over chlorinate the pool.

You need to put the pump or SWG on a timer so you can control the hours the SWG runs. The Intex pump above has a built in timer to control the cycles the pump runs.

Intex SWG - Further Reading

www.troublefreepool.com

 

[shoyru177177]

Thank you for your advice! I will spend some time letting it all soak in and doing some more research.