Is my SWG insufficient for the size of my pool?

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J

Jahlon

Active member
Aug 2, 2024
27
Sewell, NJ
Hi all - I just discovered TFP today after being frustrated with pool stores/companies over the last year. I moved into my house with a pool in late 2022, so this is my second season with it and it has been a struggle keeping it maintained. It seems that no matter what I do, I get algae buildup during the week which becomes a big chore every weekend to clean.

One of the first things I did when I moved in was have a SWG installed. I contacted a pool company and they installed a Hayward Goldline TurboCell TCELL925. I didn't know anything about the different options, but it was what the pool guy recommended.

Over the last couple weeks I've had my pool water tested at a pool store, and my chlorine has been low. I've been trying to determine what percent output setting I need to keep the right chlorine level - I already had it at 85% with the pump running at 8 hours/day, but chlorine was still coming up as essentially 0. There is no visible buildup on my salt cell - it looks totally clean. And my salt has been good (~3200 ppm). Over the last week, I've had it running at 100 percent - and I'm still seeing green accumulate. Going to test my water again tomorrow, but I'm expecting the chlorine is STILL low, based on what I'm seeing.

After educating myself with TFP and Pool Math all day, I think I've discovered that this TCELL925 is just not sufficient for my pool. My pool is about 20x40 ft (rectangular) and goes from about 3ft to 8ft. Pool Math estimates my pool volume is 35906 gallons (I put in 6ft for "average depth" - just averaged 3 and 8 to get 5.5 and rounded up...not sure if that's the best way to do it). On Hayward's website, the TCELL925 is rated for up to 25000 gallons - significantly less than my pool's estimated volume. To me, this seems like a very reasonable explanation why I'm having trouble with my chlorine, and therefore algae.

Can someone sanity check me on this? If I'm interpreting this all right, I'm going to contact the company that installed it... And insights/recommendations are greatly appreciated!
 
Your pool is more likely about 30K gallons.
Your cell is undersized, and at 30K, puts out about 3.7 FC.

First thing you need to do is get a recommended test kits. Link-->Test Kits Compared

Why? We don't trust pool store testing. It is notoriously inaccurate. Giving advice on pool store test results, we could do more damage than good.

I'd add 3ppm per day of liquid chlorine in addition to your cell output until you test kit arrives.

When it arrives, post a full set of results here, and follow the SLAM process to clear the pool. Link-->SLAM Process

What controller do you have for the Tcell?
 
Welcome to TFP.

Yeah, the 925 is too small for your size pool. That pool company is clueless about how a SWG works.

If you want to stick with that cell until you use it up you need to run your pump 24/7 at a 70%-90% output level. That should give you enough daily chlorine generated.

In NJ this time of year your pool uses 2PPM - 3 PPM/day. That is within the cells 24 hour generating capacity.

And get your CYA up to 70-80 ppm.

My pool is using 2ppm/day with CYA 70 in Northern NJ.

Once you deplete the 925 cell replace it with a 940 cell which you can run at a lower %.

If your pool has picked up algae during this experiment then you need to follow our SLAM Process using liquid chlorine once you get your test kit.

Algae Archives

www.troublefreepool.com www.troublefreepool.com

www.troublefreepool.com

Pool Care Basics Archives

Your one-stop shop for all things TFP to include: ABCs of Water Chemistry, Recommended Chemicals/Levels, Test Kits, Troubleshooting, and much more!
www.troublefreepool.com www.troublefreepool.com
 
PoolStored said:
Your pool is more likely about 30K gallons.
Your cell is undersized, and at 30K, puts out about 3.7 FC.

First thing you need to do is get a recommended test kits. Link-->Test Kits Compared

Why? We don't trust pool store testing. It is notoriously inaccurate. Giving advice on pool store test results, we could do more damage than good.

I'd add 3ppm per day of liquid chlorine in addition to your cell output until you test kit arrives.

When it arrives, post a full set of results here, and follow the SLAM process to clear the pool. Link-->SLAM Process

What controller do you have for the Tcell?
Click to expand...
Yes agreed - time to take this all into my own hands. Going to look into getting a test kit - would you have a specific one you'd recommend? There were like 3 options given but idk the difference...

In addition to adding chlorine for now, do you think it's worth reaching out to the pool company that installed it and seeing if they can swap it out for one that's actually correctly sized?

The controller I have is an AquaRite 900.
 
ajw22 said:
Welcome to TFP.

Yeah, the 925 is too small for your size pool. That pool company is clueless about how a SWG works.

If you want to stick with that cell until you use it up you need to run your pump 24/7 at a 70%-90% output level. That should give you enough daily chlorine generated.

In NJ this time of year your pool uses 2PPM - 3 PPM/day. That is within the cells 24 hour generating capacity.

And get your CYA up to 70-80 ppm.

My pool is using 2ppm/day with CYA 70 in Northern NJ.

Once you deplete the 925 cell replace it with a 940 cell which you can run at a lower %.

If your pool has picked up algae during this experiment then you need to follow our SLAM Process using liquid chlorine once you get your test kit.

Algae Archives

www.troublefreepool.com www.troublefreepool.com

www.troublefreepool.com

Pool Care Basics Archives

Your one-stop shop for all things TFP to include: ABCs of Water Chemistry, Recommended Chemicals/Levels, Test Kits, Troubleshooting, and much more!
www.troublefreepool.com www.troublefreepool.com
Click to expand...
Oh man... Idk how much electricity costs where you are, but running my pump 24/7 all summer will cost me a fortune... I think either swapping out the cell or supplementing with liquid chlorine would be way less expensive.

Dumb question, but when you say "used up", what do you mean? How long to these salt cells last? How do they get "used up"?
 
What manufacturer and model pump do you have?
If it's VS (Variable Speed), what rpms does it run at?
 
Jahlon said:
Oh man... Idk how much electricity costs where you are, but running my pump 24/7 all summer will cost me a fortune...
Click to expand...

My fully loaded electrical cost is 0.26/kwh.

My VS pump runs 24/7 at 1400 RPM at 200 watts. That is $1.32/day or about $40/month.

Jahlon said:
I think either swapping out the cell or supplementing with liquid chlorine would be way less expensive.
Click to expand...

Work the numbers.

Jahlon said:
Dumb question, but when you say "used up", what do you mean? How long to these salt cells last? How do they get "used up"?
Click to expand...

A cell can last 6,000 to 10,000 hours or 365 days running at 100%.

It should give you two seasons.
 
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ajw22 said:
My fully loaded electrical cost is 0.26/kwh.

My VS pump runs 24/7 at 1400 RPM at 200 watts. That is $1.32/day or about $40/month.



Work the numbers.



A cell can last 6,000 to 10,000 hours or 365 days running at 100%.

It should give you two seasons.
Click to expand...

I don't actually know how many W my pump runs at (or how to figure that out), but I'm assuming it's something like 2 kW per hour (Google says average for single speed pool pumps is 1800-2500 W). My electric cost is similar to yours ($0.27 per kWh according to my last bill). By my math running 24 hours vs 8 hours would cost me ~$259 more a month.

I've never dealt with having to use liquid chlorine, so idk how much that would cost me per month for what I'd need.

Maybe I need to get a VS pump...if my assumption about my pump's wattage is correct, I'm paying 10x more than what you are...
 
Your motor pulls 6.2-6.8 amps at 230V which is about 1,500 watts or 1.5KWH or .39/hour.
 
As you've gathered, the SWCG doesn't care about pump speed, as long as it is just enough to keep the flow from tripping the flow switch. Time running and the % setting determine the total amount of Cl generated in a day. So upgrading to a VS motor will recover your costs in electricity VERY quickly. Then you can run your SWCG 24/7 until it needs a new cell, and later upgrade to one that generates more Cl. Or, if you can negotiate with the pool company successfully, you might get them to forgo some of the costs for the pump, maybe even a cell upgrade now (no labor for the install, etc.)
 
1 gallon of 10% liquid chlorine costs $6-10/gallon and gives you 3ppm or $2-$3/ppm.

So 3ppm/ day with liquid chlorine costs you $6-10.

Running your pump 24 hours at .39/hour costs you $9.36/day to generate the 3ppm of FC with the sunken cost of your cell.

I call it a wash depending on where you can buy the liquid chlorine and considering the costs of lugging the jugs.
 
Using the numbers in this thread, that means currently for 8 hrs, the pump is costing you $3.12 per day. Augmenting the generator with liquid might add $1-3 per day (wild guess). Going with a VS, using the above 24/7 would be $1.32 per day - and give you enough Cl to not go green.
Perhaps $400-900 per pool season to offset the cost of the new pump, until you hit break even.
 
Jahlon said:
Out of curiosity, do you know what the "/115V" and the "/13.2" (after MaxAmps) mean?
Click to expand...
Your pump can run at either 115V or 230V. If it is wired for 115V it will pull 13.2 amps. About the same watts either way.
 

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