Brand Spanking New Homeowner with Old Pool - Tested Pool with TF Pro for 1st Time - Help!

[SJPoe]

The 'chemists' here will scream at the inaccuracy...but heres a thing you can try to get a 'sanity' read on things.

You have a test-tube with graduated markings, so you can make an approximate diluted sample to validate your testing.
Take your 10ml of pool water, and add 10 ML of distilled or bottled water (or tap water if you are like me and on a well that has no chlorine). Take 10 ML of that combined water and add another 10 of "clean" water. You're now at 1/4 strength pool water. Take 10ml of that water and run your test.

Your 27ppm should test as roughly 7ppm (with a 10ml sample, divide drops by 2 = PPM). Its not going to be super accurate, but enough for a sanity check, and should dilute the OTO test to be on the scale.
If that is consistent between both the FAS/DPD (powder + drops) and the OTO test (the block test), then I'd be confident in your testing numbers, as it'd be unlikely that BOTH tests are off by 400%.

I'd also look at where you are testing - if you are running tabs in a fix feeder, are you sampling the water close to a return jet where the concentration would be the highest ? Are you getting water from close to the floating feeder ? Maybe sample from the entrance to the skimmer, where (in theory) the concentration should be lowest.

 

[sande005]

When measuring, note that the water surface in the tube curves up the sides (the "meniscus"). The bottom of the curve should be at the line. Not doing it with regular testing won't skew things much. But it may throw off the dilution test a bit more if not paid attention to.

As @JamesW noted, with your normal comparator test such a bright orange, you are way over 5 ppm in Cl, but you don't know how much over. Likely the pool store test has the same limit, and they too couldn't measure higher levels. That test isn't all that helpful in most instances, except to answer "do I have any Cl at all?" The powder/drop test is the "how much do I have?" test.

@SJPoe's suggestion is great. It brings both tests down to be "in range" for each, so can give you a reasonable way to use one to check the other. One may be off a few points from the other, but not a wild difference.

And - since you seem to be getting the other tests in hand, the drop size for the Cl test should be about the same as those from the other tests.

 

[platanitoz]

Happy Monday, friends. I wanted to follow up on my initial attempts with some post-10/28 updates and questions.

I went ahead and removed the Chlorine tablets, stopped using the comparator block for FC readings, and adhered to the tips about the R0871 static charge and CYA readings.

My results are the following:

• FC - 6.5
• pH - 7.5
• TA - 70
• CYA - 90
• Calcium - 200

I've continued to also take pool water the day of my own testing, and bring it to Pinch-A-Penny (old pool maintenance provider) to get a free reading to compare and contrast (see attached).

My questions are the following:

1. I'm showing via the Pool Math app that the FC range should be 7.0-12.0. On the pool maintenance records who have serviced this pool years before my ownership of it, they show the "Ideal Level" being 2-4. They seem to be using the same reagents and method. Would there be a reason for such a delta between ranges? Is it because my CYA is high, and as such the ideal FC is a dependent variable? (It is a bit nerve-wrecking as a parent of a toddler as to what should be my North Star with regards to ideal Chlorine (and other chemical ranges), so please be patient with me in your answers.)
   
   
2. Dependent on your answer to #1, when I do need to add liquid chlorine, should I just be purchasing Pinch a Penny's "jug" and going there for refills when I run out? Or do you have a preferred brand/source/method?
   
   
3. Although the same somewhat applies for the pH levels (Pinch's is 7.4-7.6, Pool Math's is 7.6-7.8), when my levels were on the high side both had the recommendation with Muriatic Acid. Pinch sold me a gallon of Muriatic which states 31.45% Hydrochloric Acid (no mention of 20 Baume). I assume that's already implied, but wanted to confirm?
   
   
4. Also, regarding the Muriatic, Pinch's instructions is to pour it into a plastic bucket already filled with pool water in a ratio of 1 part acid to 5 parts water, adding that mixed solution to the deep part of pool with pump already on. And then to not add more than a gallon of Muriatic per 8 hrs, and testing pH after 24 hrs. This is a bit different than what's on the bottle, which is pour directly into the pool (but no more than 1 quart every 12 hours. Are either methods acceptable?
   
   
5. For CYA/Stabilizer, Pinch's "ideal level" is between 40-100. On Pool Math, it says 40-50. I'm clearly way above Pool Math's range. (I've also attached pics of the vial filled to 100 mark in a previous chem test, just in case anybody thinks I'm being too lenient or strict with my reading.) How drastic of a drain/refill should I be doing to attempt to get to a 45ppm? Is it just to constantly fill above the skimmer and then drain to the skimmer liner where it would almost become an issue for the pump to further drain and repeat x times?
   
   
6. For Calcium Hardness, Pinch's ideal level is between 250-400; Pool Math shows 350-550. With my 200-225pm result for the past 3 weeks and a Pool Math target of 450, is the app's recommendation of adding 42-46 lbs of Calcium Chloride in one sitting accurate?

Thanks to @PoolStored, @JamesW, @mknauss, @SJPoe , @sande005 and @dereksanders for all their insights and guidance thus far. The patience and understanding for newbies like me has been very much appreciated.

 

[sande005]

About the FC reading: Keeping it almost too simple for the real chemists to tolerate....(but at my comprehension level!):

CYA binds with CL in the pool, leaving a small part of it to actually be active for killing algae, etc. As the active amount gets used up (algae, sunlight, etc.) some of that trapped in the CYA is released to become active. So the CYA acts as a reservoir to replenish Cl during the day. It won't give up a huge amount, but does help to keep things steady. Without it, your Cl levels will be swinging wildly in a short time, and algae can get started easily.
BUT - all the practical non-laboratory tests (ours or pool stores) measure both the active Cl AND that trapped by the CYA, as one number - "FC". So yes, as the CYA goes up, the total FC has to go up, to ensure that there is enough active portion available to do the job.
As CYA rises, it takes more and more Cl added to get to and maintain the high levels needed. TFP's levels are a reasonable balance between the two - enough protection offered by the CYA, but with an eye toward keeping Cl additions manageable. One can run at higher CYA levels than recommended - but it takes proportionally more Cl added constantly to maintain the desired range. Eventually, if CYA rises too much, it becomes a money saver to do a pool drain and refill, rather than buying large amounts of Cl constantly. (CYA only rises if you add it - either as stabilizer or included as part of something else, like chlorine tablets).
Hand in hand with the increasing amount of Cl needed with an increase in CYA is the need to go even higher if one needs to combat an algae outbreak. TFP's "SLAM" levels. These, when maintained consistently over a time period, have proven to be enough to get rid of algae, but be very safe for swimming. As you can see from the chart, they seem lot higher than the recommended levels - but it is the active Cl that we can't directly measure that counts, not the combined FC number.

So, why do so many recommend keeping the FC numbers low, regardless of the CYA level? Some here will point to an economic motive - there is a LOT of profit to be made in pool store potions, and having pools go green drives those sales. I tend to think it may be more of a glacial slowness - the NIH, FDA, EPA, and all the other agencies involved are extremely slow to update their advice. They generally focus on commercial pools, and not home pools, anyway. Therefore pool companies don't want to buck the status quo - what was good for the 1950's is good enough for now. The low levels commonly stated are definitely in the safe zone, and the worst that happens is a pool turns green - and is not a big risk to a lot of people, like a commercial/public pool may become.

Where to buy? Home Depot, Wal-Mart, Pinch-a-penny - whoever has the current best price. Note that liquid Cl does loose strength moderately quickly, so buy where you can get the freshest and not leftovers from last year.

 

[SJPoe]

My results are the following:

• FC - 6.5
• pH - 7.5
• TA - 70
• CYA - 90
• Calcium - 200

I've continued to also take pool water the day of my own testing, and bring it to Pinch-A-Penny (old pool maintenance provider) to get a free reading to compare and contrast (see attached).

Trust your own testing, but always interesting to see how close the store is. In your case, pretty close

My questions are the following:

1. I'm showing via the Pool Math app that the FC range should be 7.0-12.0. On the pool maintenance records who have serviced this pool years before my ownership of it, they show the "Ideal Level" being 2-4. They seem to be using the same reagents and method. Would there be a reason for such a delta between ranges? Is it because my CYA is high, and as such the ideal FC is a dependent variable? (It is a bit nerve-wrecking as a parent of a toddler as to what should be my North Star with regards to ideal Chlorine (and other chemical ranges), so please be patient with me in your answers.)

Your (edit) recommended FC level (/edit) is dependent on your CYA. The higher your CYA, the higher your FC needs to be in order to effectively sanitize your pool. The industry is very very behind the science on this issue. Pool Math is correct, and you should aim for 7-12 FC. Your fear is the pool will be 'chlorine-y' or will irritate your eyes, but the fact is that if you keep the correct FC/CYA ratio, you simply don't get these problems.

FC/CYA Levels

• Dependent on your answer to #1, when I do need to add liquid chlorine, should I just be purchasing Pinch a Penny's "jug" and going there for refills when I run out? Or do you have a preferred brand/source/method?

Add liquid chlorine based on the recommendation in Pool Math to maintain a FC level around 10. Your LC can be sourced from anywhere, and there is a LONG thread about good places to buy it. Generally best to dose in the morning so you get the higher levels during the daylight.

• Although the same somewhat applies for the pH levels (Pinch's is 7.4-7.6, Pool Math's is 7.6-7.8), when my levels were on the high side both had the recommendation with Muriatic Acid. Pinch sold me a gallon of Muriatic which states 31.45% Hydrochloric Acid (no mention of 20 Baume). I assume that's already implied, but wanted to confirm?

Might be cheaper at the local hardware store (in the paint section usually) - Baume is a measure of density, where as the 31.45% is a measure of the concentration of the acid ions themselves. For the purposes of this discussion, 20 baume = 31.45% when it comes to Muriatic Acid.

• Also, regarding the Muriatic, Pinch's instructions is to pour it into a plastic bucket already filled with pool water in a ratio of 1 part acid to 5 parts water, adding that mixed solution to the deep part of pool with pump already on. And then to not add more than a gallon of Muriatic per 8 hrs, and testing pH after 24 hrs. This is a bit different than what's on the bottle, which is pour directly into the pool (but no more than 1 quart every 12 hours. Are either methods acceptable?

Its not Nitroglycerine...but it is nasty stuff. Don't get it in your eyes or on your clothes if you can help it. Rinse thoroughly if you do. I use it mostly in the hot-tub, and I just add it using a plastic cup directly into the tub. If you can add it to a spot where these is plenty of flow, thats good. Don't add directly to the skimmer basket, as this would massively elevate the acidity in the pump/filter/heater equipment for a while as it circulates, and that's not a good thing to do. This pretty much applies to most chemical additions.

• For CYA/Stabilizer, Pinch's "ideal level" is between 40-100. On Pool Math, it says 40-50. I'm clearly way above Pool Math's range. (I've also attached pics of the vial filled to 100 mark in a previous chem test, just in case anybody thinks I'm being too lenient or strict with my reading.) How drastic of a drain/refill should I be doing to attempt to get to a 45ppm? Is it just to constantly fill above the skimmer and then drain to the skimmer liner where it would almost become an issue for the pump to further drain and repeat x times?

For details on a no-drain water change, check here

• For Calcium Hardness, Pinch's ideal level is between 250-400; Pool Math shows 350-550. With my 200-225pm result for the past 3 weeks and a Pool Math target of 450, is the app's recommendation of adding 42-46 lbs of Calcium Chloride in one sitting accurate?

Sounds about right. I have a vinyl liner pool, so Calcium Hardness isn't a big deal for me, but I trust in PoolMath, and if it recommends 450, and that you need 40lbs, then it's probably right. I would probably add half first, re-test after a couple day and then add the rest as needed. Your Calcium is important, as it is a component in the Calcium Scaling Index, which you should be looking to get as close to 0 as possible. Over 0 equals a possibility of calcium scaling, under 0 is a possibility of calcium leaching from your plaster) so getting this balanced is important.

Thanks to @PoolStored, @JamesW, @mknauss, @SJPoe , @sande005 and @dereksanders for all their insights and guidance thus far. The patience and understanding for newbies like me has been very much appreciated.

 

[PoolStored]

1. I'm showing via the Pool Math app that the FC range should be 7.0-12.0. On the pool maintenance records who have serviced this pool years before my ownership of it, they show the "Ideal Level" being 2-4. They seem to be using the same reagents and method. Would there be a reason for such a delta between ranges? Is it because my CYA is high, and as such the ideal FC is a dependent variable? (It is a bit nerve-wrecking as a parent of a toddler as to what should be my North Star with regards to ideal Chlorine (and other chemical ranges), so please be patient with me in your answers.)

Your pool, equipment and toddler are safe to swim in pool water that has up to SLAM level FC for your CYA.

Pool Water Chemistry

This thread presents my findings so far on pool water chemistry including the following: More Accurate Calcite Saturation Index (CSI) to replace Langelier Saturation Index (LSI) Calculation of ppm HOCl (disinfecting chlorine) at various levels of Total Free Chlorine (FC) and Cyanuric Acid (CYA)...

www.troublefreepool.com

1. Dependent on your answer to #1, when I do need to add liquid chlorine, should I just be purchasing Pinch a Penny's "jug" and going there for refills when I run out? Or do you have a preferred brand/source/method?

Pinch a penny is an excellent source.

Basic Pool Care Schedule

This basic pool care schedule can guide you in creating your own pool care routine. Regular pool maintenance will keep your water sparkling!

www.troublefreepool.com

1. Although the same somewhat applies for the pH levels (Pinch's is 7.4-7.6, Pool Math's is 7.6-7.8), when my levels were on the high side both had the recommendation with Muriatic Acid. Pinch sold me a gallon of Muriatic which states 31.45% Hydrochloric Acid (no mention of 20 Baume). I assume that's already implied, but wanted to confirm?

Not sure your question here, but any pH in the 7s is just fine. A TA of 60-80 is ideal. When your TA is between 60-80, I'd just maintain a pH of 7.8. When it gets to 8.0, reduce it again to 7.8. No need to drive it lower.

1. Also, regarding the Muriatic, Pinch's instructions is to pour it into a plastic bucket already filled with pool water in a ratio of 1 part acid to 5 parts water, adding that mixed solution to the deep part of pool with pump already on. And then to not add more than a gallon of Muriatic per 8 hrs, and testing pH after 24 hrs. This is a bit different than what's on the bottle, which is pour directly into the pool (but no more than 1 quart every 12 hours. Are either methods acceptable?

Pour it slowly from the jug into the pool, over a return, with the pump running. Don't pre-mix. The less handling of acid the better. You can even set the jug on the pool water when you are pouring to support the weight of the jug.

1. For CYA/Stabilizer, Pinch's "ideal level" is between 40-100. On Pool Math, it says 40-50. I'm clearly way above Pool Math's range. (I've also attached pics of the vial filled to 100 mark in a previous chem test, just in case anybody thinks I'm being too lenient or strict with my reading.) How drastic of a drain/refill should I be doing to attempt to get to a 45ppm? Is it just to constantly fill above the skimmer and then drain to the skimmer liner where it would almost become an issue for the pump to further drain and repeat x times?

When CYA is 90 or above, do a diluted test here, starting at #8.

CYA - Cyanuric Acid Test

Cyanuric acid (CYA) is the chemical name for the product commonly called “pool water stabilizer” … Read more…

www.troublefreepool.com

CYA will degrade over time. If you can keep your FC 10-12, when you test, then just let it come down over time. When I say "when you test," I mean it should be 10-12 when you test...if you need to dose higher, so that you are always in range (10-12) when you test, then dose higher.

1. For Calcium Hardness, Pinch's ideal level is between 250-400; Pool Math shows 350-550. With my 200-225pm result for the past 3 weeks and a Pool Math target of 450, is the app's recommendation of adding 42-46 lbs of Calcium Chloride in one sitting accurate?

I would add enough calcium chloride to raise your CH to 250. Test your fill water for CH and report back.