jellmers

New member
Mar 18, 2021
3
Plymouth
Hi,

We are new to the pool game having just moved to a house with a pool...

Left for us was a Scuba II Electronic pool tester, that measures Chlorine in mg/l (0.1 to 6.0) and all other measurements in mg/l as well apart from pH obviously....

How does that relate to the logging units of the PoolMath app, which I believe uses calculations based on ppm?

There doesnt seem to be a way to change this in the settings....

Help needed to make sure I am not 'over chlorinating' the water we swim in.
 
Welcome to TFP :)

As long as your FC/CYA Levels following this chart you will be goo..

1 mg/L = 1 parts per million (ppm)

You really need to get a drop based system, the electronic really do not work great and you have to continually calibrate them.. I love my TF100 :)
 
Hi there Jellmers, welcome and congrats on the new pool :snorkle::swim:

Automatic pool testers are often inaccurate because of poor upkeep and calibration. We don't recommend them. We believe the best way to test a pool is with a drop based kit. Taylor reagents are the gold standard for drop based kits and both of the kits we recommend use Taylor's.

Either the TF-100. from. www.tftestkits.net. or the Taylor K-2006C kit. You NEED the FAS-DPD tester.

More often people are under chlorinating, and end up with cloudy green pools. Not us at TFP though!

Maddie :flower:
 
Thanks. The electronic tester is calibrated each time its used, but I here what you are saying....

What I am sort of struggling with is most of the guidance online seems to suggest that chlorine levels should be maintained between 1-3mg/l (PPM) for an outside pool, yet the pool math program has my 'recommendation' target up between 4-9!?

That seems very high to me.

Granted my CYN levels are near the top end of the recommendation at 55, but still I am a little confused as to why the free chlorine is targeting at such a high level....

I am using stabilised chlorine granules (dichlor) as my chlorination method.
 
What I am sort of struggling with is most of the guidance online seems to suggest that chlorine levels should be maintained between 1-3mg/l (PPM) for an outside pool, yet the pool math program has my 'recommendation' target up between 4-9!?

That seems very high to me.

Granted my CYN levels are near the top end of the recommendation at 55, but still I am a little confused as to why the free chlorine is targeting at such a high level....
So in short, CYA greatly slows FC loss due to the sun. However it also reduces the effectiveness of FC. Based on both chemistry math and experience TFP has developed the FC/CYA chart. If you follow this then the FC is always as effective no matter the CYA level. A recommendation of 1-3 ppm with no regard to CYA level simply doesn’t make sense once you dig into the underlying chemical aspects of it. Which I can link if you really want to dive deep into it.

I am using stabilised chlorine granules (dichlor) as my chlorination method.
Dichlor will add CYA over time, which will require even higher FC levels for the chlorine to stay effective and eventually will build up to the point where you need to change some of the water to remove. We recommend liquid chlorine for general chlorination as it doesn’t
 
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The relationship between CYA (stabilizer) and Free Chlorine (FC) requires that as your CYA levels rise, your FC levels must also rise to have the same sanitation effect. The problem with using the dichlor as your primary chlorine source is the fact that the chlorine part will be consumed by sanitation and sunlight, but the CYA part will only ever be lost by removing water from the pool and replacing it. This causes CYA levels to continuously rise, causing increasing chlorine demands, until the chlorine required for proper sanitation reaches an unattainable level, and then a large water replacement in needed to bring CYA levels back into line.

For this reason, we use liquid chlorine, or salt water chlorine generator cells (SWCG) as our chlorine source to prevent the constant buildup of CYA.
 
Hi, welcome to TFP! We don't follow conventional pool industry recommendations. The problem with conventional recommendations is that they treat each chemical value as a separate entity that has no relationship to any other chemical value. For example, conventional recommendations only look at chemical values in their individual ranges, such as FC (chlorine) must be between 1-3ppm, without taking into account how other chemical values interact with each other. This is why they will say a CYA of 90 and FC of 2 are "perfect", because they both fall within the acceptable range for each value. However, CYA and Chlorine must be maintained in a proper ratio to each other. If you look at the FC/CYA Chart you will see that if CYA is 90 in a manually chlorinated pool, FC of 2 is far too low and algae will form under those conditions.

TA and pH are another example. Conventional standards want a TA of 90-120 and pH of 7.5 TA is generally only a concern when pH is difficult to balance. If you have a TA of 70 and a pH of 7.5 there is no need to adjust the TA just to meet an arbitrary value. If you do raise the TA to 90, then your pH is also going to rise. If you lower the pH the TA will also drop. pH can be 7.0 to 7.8 in most pools without causing further issues. There is no need to chase a perfect TA and a perfect pH if your pH is in the acceptable range and fairly stable. TA by itself means nothing.

pH and calcium also have a relationship to watch. Conventional recommendation for calcium is 250-450ppm and in most pools this is not a problem. However if you live in an area with very hard water it may be next to impossible to keep the calcium below 450. In that case it is important to keep your pH low, around 7.0, to prevent calcium scale formation in the pool.

Strictly following conventional recommendations can lead you to a pool full of problems if you don't know how the relationships between chemicals work. Knowing these relationships also guides what types of products to use in the pool. If CYA is high enough you don't want to use dichlor granules or trichlor tablets in your pool to provide chlorine. Both of these products contain CYA and will cause CYA to rise over time. The only way to get rid of excess CYA is to drain water out of the pool. It does not evaporate out with the water. Calcium hypochlorite adds calcium to the water along with chlorine. Like CYA, the only way to get rid of excess calcium is to drain water. Liquid chlorine is the only chlorine source that does not add either CYA or calcium to a manually chlorinated pool.

TFP has the real life experiences of thousands of pool owners, plus the opinions of professionals who have read peer reviewed research that supports our pool care method. Our methods work for the majority of private pool owners.
 
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Hi, welcome to TFP! We don't follow conventional pool industry recommendations. The problem with conventional recommendations is that they treat each chemical value as a separate entity that has no relationship to any other chemical value. For example, conventional recommendations only look at chemical values in their individual ranges, such as FC (chlorine) must be between 1-3ppm, without taking into account how other chemical values interact with each other. This is why they will say a CYA of 90 and FC of 2 are "perfect", because they both fall within the acceptable range for each value. However, CYA and Chlorine must be maintained in a proper ratio to each other. If you look at the FC/CYA Chart you will see that if CYA is 90 in a manually chlorinated pool, FC of 2 is far too low and algae will form under those conditions.

TA and pH are another example. Conventional standards want a TA of 90-120 and pH of 7.5 TA is generally only a concern when pH is difficult to balance. If you have a TA of 70 and a pH of 7.5 there is no need to adjust the TA just to meet an arbitrary value. If you do raise the TA to 90, then your pH is also going to rise. If you lower the pH the TA will also drop. pH can be 7.0 to 7.8 in most pools without causing further issues. There is no need to chase a perfect TA and a perfect pH if your pH is in the acceptable range and fairly stable. TA by itself means nothing.

pH and calcium also have a relationship to watch. Conventional recommendation for calcium is 250-450ppm and in most pools this is not a problem. However if you live in an area with very hard water it may be next to impossible to keep the calcium below 450. In that case it is important to keep your pH low, around 7.0, to prevent calcium scale formation in the pool.

Strictly following conventional recommendations can lead you to a pool full of problems if you don't know how the relationships between chemicals work. Knowing these relationships also guides what types of products to use in the pool. If CYA is high enough you don't want to use dichlor granules or trichlor tablets in your pool to provide chlorine. Both of these products contain CYA and will cause CYA to rise over time. The only way to get rid of excess CYA is to drain water out of the pool. It does not evaporate out with the water. Calcium hypochlorite adds calcium to the water along with chlorine. Like CYA, the only way to get rid of excess calcium is to drain water. Liquid chlorine is the only chlorine source that does not add either CYA or calcium to a manually chlorinated pool.

TFP has the real life experiences of thousands of pool owners, plus the opinions of professionals who have read peer reviewed research that supports our pool care method. Our methods work for the majority of private pool owners.
Thank you for such a complete answer.... I am now confident that the results from the tester I have, are what PoolMath needs (same units) and that what was resulting was not spiralling my pool chemistry out of control. :)

I also have some liquid chlorine to source and purchase I think, so that I can balance the pool and shock it at the right time, without elevating the CYN levels...

As said pools are a new thing for me and it took enough to get it to this stage after the previous owners neglected it for over a year..... but we are getting there..

Being in the UK, the use of the pool is somewhat limited but I like tech so I may look to install a home-brew automatic testing rig into the pump house at some point, but other things need fixing first :)

Thanks for all the help and support.

Jason
 
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