New member / long-time pool owner

[4ringsnbr]

I've owned my house (and pool) for 14 years now and did maintain a much larger vinyl pool when I was a kid back in the cal hypo tablet days. I'm also a chemical engineer who is very familiar with the chemistry involved in chlorine electrolysis and water balance. I had my pool replastered in 2021, so have experienced that startup process. My pool was built by the previous homeowner so I inherited it and the replaster / remodel allowed me to tweak the appearance somewhat. I have a ~12k gallon plaster pool (combined with elevated spa), Hayward TriStar main pump with Super II spa booster pump, Hayward cartridge filter, Hayward 300k Btu heater, and Hayward AquaRite SWG. My automation system, lights, and valves are Jandy, however, and do work fine with the Hayward stuff (I can control / read salt cell through the automation system with no issues). I also have a Paramount PV3-based infloor system which is very low maintenance and works quite well.
I've gotten to know my pool well enough that control is pretty routine for ease of operation. I make sure I turnover my water 3x per day in season (March - October) and 1.5x per day off season. In season I get my alkalinity down to below 60 ppm, get my CYA up to 30 ppm, and increase my SWG output slowly from 10% in March to 40% in August. I end up using about 1 gal. of acid per month in the summer and about half that rate in the winter. Once November rolls around, I'll buy a little baking soda to get the alkalinity up to 80 for the colder water temps. I try to keep my calcium above 400 ppm year round so that I can run the alkalinity lower. Nice thing about the Hayward SWG is that I can run 2400 ppm salt in the winter (with reduced output) and bump the salt up to 3000 for the swim season when I need to make more chlorine. I never buy chlorine at all.

 

[mknauss]

Welcome to the forum!

I suggest you read through Pool Care Basics - Trouble Free Pool and even look at a few of our videos TFP-TV - Trouble Free Pool

 

[Texas Splash]

Welcome to TFP!

 

[Newdude]

Hey 4rings and Welcome !!!!

Forget the turnover nonsense. Your pool needs filtering based on your surface area and how much crud is blowing around. It's a moving target that doesn't fit into any standards, even amongst neighbors. Your neighbor may have a pool with the same dimensions, twice as deep and he supposedly needs twice the gallons turned over that you do. If his trees blow into your yard, he'll need way less filtering and you'll need more. If it can vary that much for neighbors, the idea that the whole country needs a standard filtering amount it just silly.

Anywho, glad to have you.

 

[4ringsnbr]

I understand the logic behind the turnover demands-- I'm aware of the relationship between the 425 sq. ft. filter I have and the volume of the pool. The filtration is only 1 of the reasons for running the number of turnovers. The other is the fact that the SWG basically superchlorinates the water flowing through it while it is active. At the highest setting I use of around 40-50 during August, this means that the cell is only active 40-50% of the time. If you turnover the water at least 2x during the daily cycle, you get to superchlorinate the equivalent of the pool volume during peak season. The other reason for running my pump as much as I do is to keep the pool clean. The infloor cleaner requires a few hours at high speed to completely clean the pool so that I never really have to vacuum the pool. I've found over the past decade that if I keep these 3 turnovers per day during the summer, I have a much cleaner pool and really no problems with any algae or other potential pool problems. I never have to buy algaecide or chlorine-- never have to manually shock my pool by running it this way.
If you run 1 turnover per day of water, this means that 63.2% of your water is assured to go through the system (you have to think of it as a first-order process since some of the water will actually make 2 trips through the system if you think about all the molecules of water in the pool). 2 turnovers ensures that 86.5% of all the molecules go through the filter; 3 turnovers ensures that 95% of all your water goes through the filter at least once per day.

 

[Newdude]

I'm aware of the relationship between the 425 sq. ft. filter I have and the volume of the pool.

Also unrelated. A smaller filter needs cleaning more often and one doesn't out perform the other. If you have no crud blowing in mid season, neither filter needs cleaning, big or small. Surface area (of the pool) is far more of a factor than gallons.

The other is the fact that the SWG basically superchlorinates the water flowing through it while it is active. At the highest setting I use of around 40-50 during August, this means that the cell is only active 40-50% of the time. If you turnover the water at least 2x during the daily cycle, you get to superchlorinate the equivalent of the pool volume during peak season

The residual chlorine the SWG leaves in the pool keeps it sanitary if it's programmed correctly adhering to the FC/CYA relationship. Superchlorinating already sterile water which has residual FC in reserve is entirely unnecessary.

 

[Newdude]

Lemme tell you how I inadvertently 'got it right'. By dumb luck, my test strip was good and purple on week one with stupid clear water. After TFP I learned that was 8-12 FC because test strips are terrible, but for 6.5 years I chased grape lollipop purple on a test strip. . I thought I was doing it right because it worked. But what it actually was, was that I was replacing more FC per day than burned off, or replacing exactly what was lost with room to spare per my CYA level. (Which I had no idea about).

I got it right but I couldn't have been more wrong. It's a testament to how much you can goof over target range, while the same can't be said about running below target range, which is what every last other person I knew did, with nothing but headaches.

Anywho, you'll learn TONS here, from people who walked in your shoes one way or the other. We exist solely to help others not make the same mistakes we did. With science based chemistry fine tuned by hundreds of thousands over 15 years, the collective wisdom is off the charts here. You're in GREAT hands and were glad to have you. .

 

[4ringsnbr]

Also unrelated. A smaller filter needs cleaning more often and one doesn't out perform the other. If you have no crud blowing in mid season, neither filter needs cleaning, big or small. Surface area is far more of a factor than gallons.

The residual chlorine the SWG leaves in the pool keeps it sanitary if it's programmed correctly adhering to the FC/CYA relationship. Superchlorinating already sterile water which has residual FC in reserve is entirely unnecessary.

Residual FC in your pool will be converted to CC when it kills algae or encounters nitrogen compounds from bathers. If you have an SWG and make sure you get a full cycle of water through it daily while active (in the peak of the season), you'll never have to worry about shocking your water to get rid of that combined chlorine because the cell will do that as the water goes through it-- I never have to shock my pool. I've only even seen any CC show up maybe 1-2 times a year- typically early morning after a lot of swimming the day before and the pump just started up for its daily cycle-- and I've never had more than 0.5 ppm CC.
The other reason you need turnover is to keep your water circulating. In season (mid-April through mid-October), my water will be over 85 degrees and sees direct sunlight from about 8am - 6pm. If you don't keep the water circulating, you will get algae blooms in crevices as those local spots will deplete the chlorine-- with no flow, the spot will get lower and lower in FC until you get an algae bloom. The rule is (at least in the South), if direct sunlight touches your water in season, you better have your pump running.
There is a reason many local jurisdictions and governments require a specific number of turnovers for commercial pools-- it keeps them safe.

 

[4ringsnbr]

I don't use test strips--- I have a TF-100 so I do an FAC/DPD chlorine test when I want to check that; however, my ORP meter is easier since I just keep it above 700 mV in season and don't have to worry about the CYA ratio, which I keep to a minimum too since going over 30ppm and certainly over 50ppm of CYA doesn't really help you that much with UV protection.

Lemme tell you how I inadvertently 'got it right'. By dumb luck, my test strip was good and purple on week one with stupid clear water. After TFP I learned that was 8-12 FC because test strips are terrible, but for 6.5 years I chased grape lollipop purple on a test strip. . I thought I was doing it right because it worked. But what it actually was, was that I was replacing more FC per day than burned off, or replacing exactly what was lost with room to spare per my CYA level. (Which I had no idea about).

I got it right but I couldn't have been more wrong. It's a testament to how much you can goof over target range, while the same can't be said about running below target range, which is what every last other person I knew did, with nothing but headaches.

Anywho, you'll learn TONS here, from people who walked in your shoes one way or the other. We exist solely to help others not make the same mistakes we did. With science based chemistry fine tuned by hundreds of thousands over 15 years, the collective wisdom is off the charts here. You're in GREAT hands and were glad to have you. .

 

[PoolStored]

Residual FC in your pool will be converted to CC when it kills algae or encounters nitrogen compounds from bathers.

True on the nitrogen compounds, not so much on the algae...we have plenty of people with algae, and their CC is 0.

CC - Further Reading

www.troublefreepool.com

If you have an SWG and make sure you get a full cycle of water through it daily while active (in the peak of the season), you'll never have to worry about shocking your water to get rid of that combined chlorine because the cell will do that as the water goes through it-- I never have to shock my pool. I've only even seen any CC show up maybe 1-2 times a year- typically early morning after a lot of swimming the day before and the pump just started up for its daily cycle-- and I've never had more than 0.5 ppm CC.
The other reason you need turnover is to keep your water circulating. In season (mid-April through mid-October), my water will be over 85 degrees and sees direct sunlight from about 8am - 6pm. If you don't keep the water circulating, you will get algae blooms in crevices as those local spots will deplete the chlorine-- with no flow, the spot will get lower and lower in FC until you get an algae bloom. The rule is (at least in the South), if direct sunlight touches your water in season, you better have your pump running.
There is a reason many local jurisdictions and governments require a specific number of turnovers for commercial pools-- it keeps them safe.

A great read:

Turnover of Pool Water - Further Reading

www.troublefreepool.com

Circulation and turnover are two different beasts. I run mine 24x7 on very low speed. I do that for my SWG, less so for skimming. I doubt I get even 1x turnover. You are right too, there can be situations with pools that have poor circulation, even with multiple turnovers that have trouble spots.

The reason for the commercial pool rules are mainly due to the higher bather load.

I don't use test strips--- I have a TF-100 so I do an FAC/DPD chlorine test when I want to check that; however, my ORP meter is easier since I just keep it above 700 mV in season and don't have to worry about the CYA ratio, which I keep to a minimum too since going over 30ppm and certainly over 50ppm of CYA doesn't really help you that much with UV protection.

An ORP sensor does not know how much CL is bound with CYA that can be freed as needed. So an ORP system with high CYA will think that CL is low when it is not. There are studies and data that show water with an ORP at 650mV (considered "sanitizing" by CDC standards) that have little correlation to the exact active chlorine (hypochlorous) concentration in the water sample. So, what this means is that in practice you need to not only be able to get your ORP probe to register and maintain a voltage at the correct "sanitizing" level BUT also ensure that the ORP voltage correlates to an appropriate FC/CYA ratio. There are many factors that can influence the ORP reading and so one has to carefully study what their pool is doing OR simply setup the system and "hope" an algae bloom doesn't occur or no one gets sick. And, once that correlation is known, it has to be tracked over time as changes in the water chemistry can cause drift. ORP sensors tend to have issues too, except those pools that are covered and have CYA levels below 20-30ppm, and even then there are still issues. As long as you are testing with your TF and maintaining FC/CYA ratio to confirm ORP, you are good to go!

I would say it's A LOT easier to simply use a good test kit to measure your water on regular basis and correct the chemistry as needed than "hope & pray" the probes are working right (not saying you are doing that because you indicate you test with your TF-100, but we have more than a few that take this approach). With an SWG pool, once you get the FC level dialed in for the specific pump runtimes you use, the FC levels drift very slowly and predictably. Initially one will do a lot of testing to learn how their water behaves but, once that initial break-in period is done, a seasoned pool tester can practically guess what their water chemistry levels are and be within 10-20% of the right answer.