Why does the pool store keep saying everything is fine?

[MainePool207]

Waterlink data mate results:

pH 7.6
FC 7.73
Total Chlorine 7.83
CH 151
CYA 135 (or 108)

Water is clear, but with a few spots of yellow algae.

Now, briefly, new pool owner. Just bought the house with the pool. They left behind the granules (sodium dichloro). During the house closing, they reported using about 1 cup of the granules a night with a weekly shock during the pool season. I couldn't find any left over shock bags but I presume it came from Walmart.

When we opened the pool, we had to put in, I would estimate 20-some-odd thousand gallons. The corners of the vinyl liner actually pulled out and had to be fixed because there was so little water. Re-filled with city water.

I hadn't found this website yet so I just wung it. Went to a pool store and they used small vials for testing. "Everything is good" (direct quote) and that I had "zero chlorine in the pool." That made sense to me as I hadn't put anything in it and I replenished a very large quantity of water. They suggested I pour in twice the normal nightly dosage to get going. I did, and then did 1 cup for the next two nights.

We had the algae show up (the pool really did look "perfect" at this point). We had quite the clump of leaves at the bottom during opening, but they had been removed. Poured in one container of the clearview poly 60 and "shocked" the pool. I diligently went to Walmart, grabbed four bags, mixed it up with my broken umbrella rod and dumped it in. I then brushed all over the floor of the pool. The algae was only in spots so it was not out of control.

The algae seemed to go away but I wanted to test the water before Memorial Day. Went to a different store and they had the waterlink software. Yeah, I ended up leaving with $120 worth of calcium flakes and baking soda..........

Otherwise, "everything was fine!" I went from 0 chlorine to 13.1 FC. They simply said, let it dissipate over night, you'll be fine. The normal range was 1-4.

They wanted me to add 30 pounds of this and 40 pounds of that. I didn't. I put less than half of each in after starting my serious pool research.

It was at this point that I started to read this forum and see the relationship between CYA and FC. This Waterlink test showed CYA of "OVR 149ppm."

Yikes.

After the holiday, I had the water tested again but at a different store. They too used the Waterlink. FC dropped to 8 and CYA was now at 108ppm.

? I didn't understand this wild swing and I asked the person. She gave a wild guess but told me the CYA was fine (within the normal range of 30-150). I asked if the CYA was keeping my FC high and she replied, "the CYA has nothing to do with the chlorine."

She told me to let the FC dissipate over night but "everything is fine!"

At this point I'm frustrated and my TF kit has not arrived yet. I can only rely on these (what now seem to be) erroneous readings. I will say that my FC and pH levels all remained the same between tests.

I had one more test done this morning at ANOTHER STORE with a waterlink tester. The results are what you see at the top of this post. "Everything is fine!" just let your FC drop to the 1-4 level.

Why does everyone say my pool is fine?

I apologize for the long post but every time I went to a store, I tried to tell this story and they would only half listen.... and then only to be told that my pool is good to go.

Does my FC level drop slowly because I have CYA in the pool? Or, what appears to be, a lot of CYA?

Secondly, will the TF-100 test show my FC levels higher than 10 if I really do have a high CYA level? I would be disappointed if I couldn't read a higher FC level as draining the pool is less of an option right now. I'm surprised that it would be that high after a serious re-fill. Unless they've been dumping those granules in for so long.

Thank you for any insight.

 

[Texas Splash]

Hello and welcome to TFP!


You have experienced first-hand what we try to warn folks about every day here at TFP. Pool store clerks are either ignorant about chemical relationships, don't care at all, or simply perform testing inaccurately. Usually it's a little of all three. YES - Your TF-100 will certainly test FC over 10. IT will go quite high actually. But now we need to see what damage has been done by the pool store advice right? So first & foremost when the test kit arrives, do the CYA test first. If it seems to be at 100, then do the following:

CYA Dilution Testing:
Add pool water to bottom of sticker.
Add tap water to top of sticker.
Shake.
Pour out half so mixture is to bottom of sticker.
Add reagent to top of sticker.
Shake.
Test outside with back to sun and tube at waist level.
Pour back and forth a few times to see if you get the same result.
Double the result.

Let us know what you get and report back. We'll take care of you and your pool.

- - - Updated - - -

FYI - Fc drops for two reasons ... algae and/or the suns UV. CYA helps protect FC ... to a point. If it gets too high, there's an imbalance that can effect sanitation.

 

[tim5055]

Secondly, will the TF-100 test show my FC levels higher than 10 if I really do have a high CYA level? I would be disappointed if I couldn't read a higher FC level as draining the pool is less of an option right now. I'm surprised that it would be that high after a serious re-fill. Unless they've been dumping those granules in for so long.

Thank you for any insight.

The TF-100 has two chlorine tests in it. The first is in the blue box. You fill the vial with water, put in drops and it turns yellow. Matching the color of yellow tells you the amount of chlorine. This is known as an OTO test.

The second is what is known as a FAS/DPD test. You add the specified amount of pool water to the vial and place one heaping spoon of the powder in the water and it turns pink. You then add drops of reagent to the vial, counting drops until the water turns clear. The count of drops tells you the FC level. This test has a limit of 50 ppm FC

 

[Isaac-1]

First off Welcome, second of all, stop going to pool stores, as you can now see the advise they give and the testing they do is questionable at best, once you get your TF-100 in and get some reliable test numbers we can address a game plan. If your CYA is even in that ballpark though, chance are you will have to replace a substantial amount of water, all thanks to that unfortunate excessive use of dichlor.

 

[Richard320]

Welcome!

There's going to be a steep learning curve for about two weeks, but once you have a proper test kit and a little hands-on learning with testing and dosing, it'll be a breeze. And you'll never ever have to go into a pool store again unless you need obscure bits of hardware.

And by the way.... If your CYA is into triple digits, your double-digit FC isn't too high. The fact that you see algae indicates it's probably too low! The FAS-DPD tester can measure up to 50 FC, so no worries there.

 

[MainePool207]

I wanted to start by saying thank you to all of the responses.

Life got in the way, but I've finally received my TF kit. I wanted to start right off with the CYA.

Predicting a high amount, I diluted my pool water 50:50 with tap water.

I understand the black dot should become obscure at the end of the test, but HOW obscure? It had become clouded over at 80, but I could still see it. I was swirling the sample as I dropped the reagent. It got to 65 when I absolutely could not see it anymore. I think this is the right proceedure.

Please correct me if I'm wrong.

I take it to mean my CYA is 130ish?

Thanks!

 

[Richard320]

I wanted to start by saying thank you to all of the responses.

Life got in the way, but I've finally received my TF kit. I wanted to start right off with the CYA.

Predicting a high amount, I diluted my pool water 50:50 with tap water.

I understand the black dot should become obscure at the end of the test, but HOW obscure? It had become clouded over at 80, but I could still see it. I was swirling the sample as I dropped the reagent. It got to 65 when I absolutely could not see it anymore. I think this is the right proceedure.

Please correct me if I'm wrong.

I take it to mean my CYA is 130ish?

Thanks!

Exactly.

 

[zea3]

Since the previous owners were using copious amounts of dichlor, it is not surprising the CYA is so high even after a significant water exchange. The original CYA level must have been near 300ppm! Bad news is you would need to drain 60-75% of the water to get CYA down to a reasonable range. You can complete the SLAM process without draining, but you would need a huge amount of bleach! It may make more financial sense to drain and refill.

 

[MainePool207]

OK!

So things are much better now. I did a 2 drains with refills over the weekend.

pH 7.5
FC 9
Total Chlorine 9.5
TA 112
CH 125
CYA 65

I ran the CYA test twice. Once diluted and once with only pool water and received the same result.

Because of my previously mentioned algae, I'm guessing this is why I have a reading of 0.5 for CC. I purchased more liquid chlorine from walmart over the weekend in preparation of raising the FC level.

Thank you all.

 

[Richard320]

OK!

So things are much better now. I did a 2 drains with refills over the weekend.

pH 7.5
FC 9
Total Chlorine 9.5
TA 112
CH 125
CYA 65

I ran the CYA test twice. Once diluted and once with only pool water and received the same result.

Because of my previously mentioned algae, I'm guessing this is why I have a reading of 0.5 for CC. I purchased more liquid chlorine from walmart over the weekend in preparation of raising the FC level.

Thank you all.

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