New to water chemistry and need some direction

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J

J3ffh

Member
Sep 26, 2023
14
Texas
Pool Size
15000
Surface
Plaster
Chlorine
Liquid Chlorine
Noob here and just received a TF-Pro kit and did some initial testing and have some questions.

Quick background: we bought a house with a pool a couple years ago and this is our first one. It was in pretty rough shape (replaced pump and filter but still needs to be resurfaced) and knowing nothing about how to maintain it, we've been having someone do it for us since. About a month ago I got an email saying that another company is taking over our weekly maintenance so the company I hired was no longer going to be maintaining it. I was a bit annoyed by this because the original company was great, but it is what it is, so I went along with it. New guy comes in and seems to be doing fine so all is well. There was one time we had a little bit of algae but it was quickly fixed and it's been nothing but clear. Couple weeks later I get a notification that he's upping his prices so I start reading about how to take care of a pool which is how I found this site and the TF testing kits.

So the kit comes in over the weekend and I do some tests, results below:
FC 18.5
CC 1.5
TC 20
CH 700
TA 90
CYA 60
pH 7.2

First thing that jumps out at me is the FC. Either I did the test completely wrong or it's insanely high. My notes for both tests over the weekend were around the same area (19.5 on one, 18.5 on the other) so maybe I'm not following the instructions correctly. Second the CH seems incredibly high along with TA and CYA both being on the high side as well. After seeing my tests, I look back at emails where the readings are noted and what chemicals were added. The one from last week said FC was 10ppm and he added 5 chlorine tabs to the floater. After reading the ABC's of Water Chemistry here last week, I'm thinking this is completely off from what he should be doing but I haven't said anything yet. I'm trying not to be the guy that reads something on the internet then questions everything the guy is doing.

This morning I took a sample to get tested to see how it compared to my tests and results are below:
TC 8
FC 8
CC 0
pH 7
Base Demand 3 drops (no clue what this is honestly)
TA 90
CH 625
Stabilizer 140 (this is CYA, correct?)
Total Dissolved Solids 1300 (no clue what this is either)

Seeing the above tests, I assume that I did screw up my FC tests pretty badly however, the FC is still pretty high and the CH and CYA are both quite high as well. I'm assuming the FC and CYA are both high due to trying to get them back to a happy medium or did CYA get too high so you have to counteract by adding more chlorine and then they'll even out? Then there is the CH which the Pool Math app basically said to drain 1/3 of the water.

At this point, I'm a bit confused on what to do. I had assumed the levels would all be normal so it would be an easier transition, but just throwing the FC and CH numbers into the Pool Math app says I need 204oz of bleach added and 1/3 the pool drained. Any recommendations on how to move forward? Do we really need to drain that much and add that much to get it back on track? Could the condition of the surface of the pool add to the problems? Is our pool guy just throwing chlorine at it to make sure no algae grows?
 
First, welcome to TFP!!!

Before we get into anything else...trust your test kit. You may have made errors in testing, we all do. I'd review this video. Equipment clean, hold reagents vertical, SLOWLY squeeze drops and let them fall under their own weight (<<---typical errors).


Second, CC of 1.5 is concerning...watch the video, read the rest of my response, and retest everything and repost results.

J3ffh said:
Seeing the above tests, I assume that I did screw up my FC tests pretty badly however, the FC is still pretty high and the CH and CYA are both quite high as well. I'm assuming the FC and CYA are both high due to trying to get them back to a happy medium or did CYA get too high so you have to counteract by adding more chlorine and then they'll even out?
Click to expand...
The only way to reduce CYA is to replace water in the pool, or wait, as CYA degrades about 5-10 per month. Pucks add CYA. When chlorinating always follow this-->FC/CYA Levels

You are safe to swim and your pool is safe for equipment up to 40% of CYA for your FC. So, your CYA is 60, you are safe up to .4*60 or 24 FC.

On the FC test, use 10ml sample (make sure it is 10!). Then every drop is .5 FC. Try it again with 10ml sample. This is the sample size you should use ongoing.
J3ffh said:
Then there is the CH which the Pool Math app basically said to drain 1/3 of the water.
Click to expand...
Same thing with the CH, use good technique (see video) and try it again. Ensure sample size. If you are at CH 700, you may want to drain some of your pool. It may in fact be a problem with the pool. Also, test your fill water and report that value (CH, like CYA can only be reduce by replacing water...if you have high evaporation and high CH fill water, you will be replacing water over time).
J3ffh said:
At this point, I'm a bit confused on what to do. I had assumed the levels would all be normal so it would be an easier transition, but just throwing the FC and CH numbers into the Pool Math app says I need 204oz of bleach added and 1/3 the pool drained. Any recommendations on how to move forward? Do we really need to drain that much and add that much to get it back on track?
Click to expand...
Again, trust your test kit results. Drop test is the gold standard. If you got sample sizes correct and you are using proper technique, drop tests are the gold standard.

FC is a consumable and need to be checked and replaced daily.

J3ffh said:
Could the condition of the surface of the pool add to the problems?
Click to expand...
Maybe.
J3ffh said:
Is our pool guy just throwing chlorine at it to make sure no algae grows?
Click to expand...
Yes, this is very typical if you have weekly maintenance. They will super chlorinate and add pucks and hope it lasts the week.

If you have to drain, do a "no-drain exchange" found here...will protect the pool from popping:

Draining - Further Reading

www.troublefreepool.com www.troublefreepool.com

Retest with proper technique. Report results to verify. Post your fill CH.

Season 1 Showtime GIF by The Chi
 
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Thanks for the reply and all the info. I’ll give it all a deeper read tonight. I did just test FC again and it was at 17.5. I made sure it was at 10ml and dropped slowly. I’ll to watch that video tonight as well to make sure I’m doing it correctly. There was no CC this time so maybe yesterday’s was human error.

Thanks again and I’ll report back after I’ve been able to read everything and watch that video.
 
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Did you get the one with SmartStir? If not, all TFPers I've ever read highly recommend a stirrer. It removes so many variables from testing...

I'm sure the experts will chime in with advice, but the DPD test for FC is not so hard.
  • Use a clean sample container. I got free ones from the local pool store. :)
  • If you have a tab dispenser or salt water chlorine generator, stay away from the return vents. (Maybe that's how your test was so high?)
  • Sample from at least 18 inches down by pushing the container mouth down to that depth and inverting down there. You'll see bubbles as it fills.
  • Fill the test tube to the 10ml line. If you see a meniscus (U-shaped curve of the water surface), the bottom of the meniscus should be on the line. If you're a tad high, you can flick out a few drops at a time with your finger. The accuracy of this 10ml directly affects results. For example, if you get 11ml, then a true 10ppm will test as 11, etc.
  • Find the little scoop for DPD powder. Either 2 level scoops or one big heaping one: exact amount doesn't matter. Just needs to be "enough".
  • Start the stirrer. Sample should turn pink. Actually if you have ~8ppm FC or greater, I'd call it red.
  • Uncap the R-0871 (Taylor number) bottle. Hold it upright and gently squeeze to make sure the tip is clear. Then turn it completely upside down, vertical over the test tube. Some bottles will start dripping immediately, so be ready to count. Others will need a further gentle squeeze. Ideally, shoot for one drop per second or slower. You are trying to let the drops get as big and fat as possible. If you have shaky hands like mine, try leaning your elbow on the table and/or two hands.
  • Every drop is half a ppm. Example: 20 drops is 10 ppm
If you don't have the a stirrer, it's all the same except stop after every "add" step - including every drop of R-0871 - to swirl the test tube. After about the 200th swirl,$45 for the stirrer will look cheap :).
 
Last edited:
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J3ffh said:
Thanks for the reply and all the info. I’ll give it all a deeper read tonight. I did just test FC again and it was at 17.5. I made sure it was at 10ml and dropped slowly. I’ll to watch that video tonight as well to make sure I’m doing it correctly. There was no CC this time so maybe yesterday’s was human error.

Thanks again and I’ll report back after I’ve been able to read everything and watch that video.
Click to expand...
Trust the test kit. Your FC is 17.5.

OUTSTANDING that your CC is 0...again, likely testing error. You get WAY better at testing VERY quickly. Don't sweat it.

Take your time with the other tests and report up...we'll get you going!
 
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generessler said:
Did you get the one with SmartStir? If not, all TFPers I've ever read highly recommend a stirrer. It removes so many variables from testing...

I'm sure the experts will chime in with advice, but the DPD test for FC is not so hard.
  • Use a clean sample container. I got free ones from the local pool store. :)
  • If you have a tab dispenser or salt water chlorine generator, stay away from the return vents. (Maybe that's how your test was so high?)
  • Sample from at least 18 inches down by pushing the container mouth down to that depth and inverting down there. You'll see bubbles as it fills.
  • Fill the test tube to the 10ml line. If you see a meniscus (U-shaped curve of the water surface), the bottom of the meniscus should be on the line. If you're a tad high, you can flick out a few drops at a time with your finger. The accuracy of this 10ml directly affects results. For example, if you get 11ml, then a true 10ppm will test as 11, etc.
  • Find the little scoop for DPD powder. Either 2 level scoops or one big heaping one: exact amount doesn't matter. Just needs to be "enough".
  • Start the stirrer. Sample should turn pink. Actually if you have ~8ppm FC or greater, I'd call it red.
  • Uncap the R-0871 (Taylor number) bottle. Hold it upright and gently squeeze to make sure the tip is clear. Then turn it completely upside down, vertical over the test tube. Some bottles will start dripping immediately, so be ready to count. Others will need a further gentle squeeze. Ideally, shoot for one drop per second or slower. You are trying to let the drops get as big and fat as possible. If you have shaky hands like mine, try leaning your elbow on the table and/or two hands.
  • Every drop is half a ppm. Example: 20 drops is 10 ppm
If you don't have the a stirrer, it's all the same except stop after every "add" step - including every drop of R-0871 - to swirl the test tube. After about the 200th swirl,$45 for the stirrer will look cheap :).
Click to expand...
Yes, I did get the SmarStir. Not going to lie, at first I thought it was kind of silly, but after doing four or so tests, I see the benefit to it already.

The DPD definitely turned the sample red. Almost a maroon really. Tested it four times now and all have been around 17.5-18.5ppm.
 
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PoolStored said:
Trust the test kit. Your FC is 17.5.

OUTSTANDING that your CC is 0...again, likely testing error. You get WAY better at testing VERY quickly. Don't sweat it.

Take your time with the other tests and report up...we'll get you going!
Click to expand...
After reading your post more in depth and watching the video, I tested again.

FC - 18.5
CC - 0
TC - 18.5
CH - 625
TA - 80
CYA - 150
pH - 7.2
CL from comparator block - orange

These numbers are looking more like the sample I took to the store so I'm guessing I'm getting a little better. CC is at 0 still so that's nice. Initially I also read the CYA tube completely wrong. The line starts at 100 and goes down, not up. So if you don't even make it to 100... yeah. I see that now.

Question though, what is the difference in the number from the pool store compared to what I'm getting? I get 18.5 in the test, they recorded 8.

I'm going to read up on your link for draining and CH for fill water is 100.
 
J3ffh said:
Question though, what is the difference in the number from the pool store compared to what I'm getting? I get 18.5 in the test, they recorded 8.
Click to expand...
You spent good money on reliable testing to be free of the pool store. Be free of them. ;)

The pool store exists to sell you chemicals, not to get it right. I'll point to your statement as 'Evidence A'. No further statements needed, your honor.
 
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You have done a great job.

I'm concerned how to came up with CYA of 150...

Follow the instructions on step 8 of these instructions to confirm your CYA is that high:

www.troublefreepool.com

CYA - Cyanuric Acid Test

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

Do the diluted CYA test outdoors, sun at your back, fill to each line, hold at your waist and glance. When the dot is obscured, take the result and double it.

When we get this result, we will have a recommendation on the amount of draining based on your CH and CYA level...

Good Job!
 
J3ffh said:
Question though, what is the difference in the number from the pool store compared to what I'm getting? I get 18.5 in the test, they recorded 8.
Click to expand...
100,000s of thousands of pool owners have come here. I can't start to tell you the number of pool store tests that failed (I am Pool Stored....) believe me LOTS. Trust your test kit, it is accurate.
J3ffh said:
I'm going to read up on your link for draining and CH for fill water is 100
Click to expand...
Test your CYA per bullet 8...then we can figure out how much to drain to get your CH and CYA in line...
 
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PoolStored said:
I'm concerned how to came up with CYA of 150...
Click to expand...
The tube's first number on it is 100. When filling the tube, the black dot disappears before I got to 100 and above 100 counts down. I checked the distance between 100 and 90, and then counted up and estimated it to be around 150. Since there are no numbers there, it's a best guess. I'll do it again when I get home today.
 
Even while doing the diluted CYA test….

Be sure to do all CYA testing outdoors, your back to the sun, tube at waist high….and glance, not stare,
at the dot.

All of this gets easier…promise! Welcome!
 
Couldn’t do the cya test outside because by the time I got home it was dark and rainy. Did it inside according to step 8, not sure how accurate that’ll make it since it was inside, cya was 200. It was just under 100 but again, that’s the first number on the cylinder.


other tests:
FC 17
CC 0
TC 17
CH 575
TA 70
CYA 200
pH 7
 
Any time your CYA results are 90 or above, you need to do the diluted CYA test as outlined in the extended test kit directions.
 
That’s what I did tonight. Filled to 7.5 with pool water, then to 15 with tap water. Mixed and poured out half and then filled to 15 with the solution.
 
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Great. If the diluted test was above 90, dilute twice.

Do it outdoors this time. Indoors tends to make the CYA test report higher than actual.

CYA test is a turbidity test (testing the cloudiness/haziness of a fluid). The cloudiness "shows up" better when there is higher levels of light. Very roughly speaking, direct overhead sunlight is around 100,000 lux, strong indirect light (i.e. shaded from the sun) is around 10,000 lux, an overcast sky is around 1000-5000 lux but varies on how overcast (which is why a bright white cloud overcast is still OK), indoors is usually < 1000 even in a bright kitchen (more typically 500 lux).

You can still test CYA on a cloudy day since it's still strong indirect light if it's light white clouds -- basically the clouds are doing the "shading" for you -- but if it's dark clouds then that would be too dim.
 
I mentioned it to the pool guy last night, he says it's high because the tabs add CYA and we haven't had any rain which typically helps control it. His plan was to let the coming winter rains naturally bring the CYA down rather than draining.
 
J3ffh said:
I mentioned it to the pool guy last night, he says it's high because the tabs add CYA and we haven't had any rain which typically helps control it. His plan was to let the coming winter rains naturally bring the CYA down rather than draining.
Click to expand...
Yes it is high because of the tabs. Rain may dilute CYA if you have an overflow. With overflow, even multiple inches of rain will reduce CYA minimally.

The real issue is that with CYA over 200, it is impossible to keep enough FC in the pool to sanitize it (kill bacteria and algae).

I would not drain, you should do the "no drain water exchange" in the draining link I provided.
 
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