Different results across 5 different test kits

[EastCoastDigs]

Hello, I'm new here and in need of help. I notice that the recommendations here differ from all the other online recommendations. I understand that these are from pool owners and their experiences. I'm wondering if someone can help me with a couple of issues.

Issue #1 - CYA
Back story, we recently acid-washed our pool due to metal staining that we could not get out with non-drain means (about two weeks ago). We drained the pool because CYA levels were in the 70s or so, and we could not eliminate the combined chlorine without using a ton of shock or liquid chlorine. We refilled our pool. I need to get the water balanced.

Not sure what my CYA levels truly are. I have tested my water at home with 3 different test kits (La Motte Color Q and Color Qpro and Taylor) and gone to two pool supply stores. The results for CYA are different enough to be concerned. My at-home kits are giving me 19-26 CYA and the pool stores are giving me 35-38 (all with the same water sample and tested in a close enough timeframe). The Taylor kit for CYA that has you fill up a tube with the black dot is showing that the tub is full and I'm still seeing the dot, which would be under 20. I'm not sure which tested level is right, and the difference is important given the small range for CYA. Which should I believe? My chlorine is not staying in the pool, so I believe the CYA is on the lower end. However, I do not want to end up with the issue I had before where I could not get the combined chlorine out of the pool because the CYA was too high.

If I add Cal-Hypo 73 to the pool at night, getting it up to about 2.5ppm or so, it's gone down to .5ppm in a couple of days. Not much combined chlorine if any. I currently have Tri-Chlor tabs in the pool because the CYA was lower, but without the Cal-Hypo at night, the chlorine is dissipating. Should I raise the CYA or shock the pool and see what happens? If I shock, how much should I do this time?

Issue#2 - PH rise
My PH continues to rise every other day. When it's at 8.1 I put in roughly 32-36 oz of Muriatic Acid to try and bring that down to 7.4/7.5, but when I check 8 hours later, it's only down to 7.7/7.8. Then one day later, it's up to 8-8.1 again. My ALK is 96 - previously down from 125 over the two weeks. The pool store tells me my PH should be 120-150. Your site is telling me to be like 60-80. Should I continue to add Muriatic Acid? How much should I add at this point? I want to find the sweet spot to avoid adding acid constantly.

Info on the pool: 17,500 gallons, in-ground plaster pool, sand filter, chlorine pool.

Current at-home readings today:

Free Chlorine: 0.5
Total Chlorine: 0.9
PH: 8.1
ALK: 96
Calcium Hardness: 270
CYA: 24

Pool store readings:
Free Chlorine: 0.9
Total Chlorine: 1.0
PH: 8.1
ALK: 92
Calcium Hardness: 232
CYA: 38

My pool is clear, for the last couple of weeks the CC has been mainly 0.1, what should I do here?

 

[reggiehammond]

I think now is a great time to start over.

Make sure you have a proper test kit and stop using pool stores, and other inaccurate means of testing that only serve to cause confusion.

Swimming Pool Test Kits Compared

What pool test kit should I buy? Why shouldn't I use test strips? Our recommended test kits will pay for themselves in no time!

www.troublefreepool.com

Read and understand the FC/CYA relationship which is paramount to avoiding algae. Your FC is way too low, and you don't have enough CYA to protect FC with warm temperatures and warmer water.

The Free Chlorine and Cyanuric Acid Relationship

Managing your cyanuric acid and Free Chlorine levels is key to stabilizing your pool. Learn how these two items affect each other.

www.troublefreepool.com

Once you have a test kit, post up results here and we can go from there. Getting your free chlorine up in the immediate need. My guess is that you've already given plenty of time for algae to gain a foothold and will need to do a SLAM to get clear.

SLAM - Shock Level and Maintain

We’ve all had to deal with a green pool. Clear algae from your pool with a SLAM! Read here to use shock level and maintain to clear your pool.

www.troublefreepool.com

CCs are just a by product of sanitation. UV (ie. the Sun) is very effective at clearing CCs. The presence of CC plus the very low FC levels point to algae.

TFP PoolMath and Pool School can really help.

Recommended Pool Chemicals

Which should I buy? TFP's recommended pool chemicals are cheap, easy, and won't unbalance your pool water.

www.troublefreepool.com

 

[Newdude]

Hey Ann and Welcome !!!!

Full stop. The pool stores and wherever else you went prior, are the reason we exist. The industry way revolves around you not maintaining your pool, then needing to shock it back to life. Weekly. When it goes south, the have lots of spendy chemicals to sell you while making up utter nonsense to sell them.

The colorQ testers have shown to be off too often for our liking. The pool store tests can be like playing blind darts sometimes. Which Taylor kit do you have ? Post results from that one and we'll go from there.

Reggie has you well covered above. Once we get through this ordeal, here's the Pool Care Basics

 

[EastCoastDigs]

Hi all, thanks for responding. In my post, I mentioned that my pool water is crystal clear, there is no algae, and I have not let my free chlorine stay low. I bump it back up with Cal-Hypo 73 when it drops. Plus, I currently have tabs in the pool too. Please don't lecture me on the tabs, I have bottles of liquid chlorine I plan to use all season. I'm only finishing off the tabs now because the CYA is so low and I have a handful left.

I have 3 test kits that I own, so I do not rely on the pool store. I also understand why this forum exists and the thoughts on pool stores, which is why I'm posting on it. I have read the articles on this forum, and I'm aware of the relationship between the FC and CYA and the PH and ALK. What I'm asking about is what to do about the CYA levels. The Taylor kit I have (K1005) is reading under 20 with the black dot test, the tube is completely full, and the black dot is maybe 1/3 faded. The digital tests I've done for CYA read 26. The pool store says 38. I don't want to go too high on the CYA, I would be happy at 40ppm. So I'm wondering how I get there without overshooting the mark. Considering all the tests I've done, is the Taylor dot test the most accurate? Do I need to shock the pool more to have the chlorine stabilize? I put about 2 lbs of shock in last week, but maybe I need to keep doing that until it holds. The combined chlorine is not too bad, and once I add another 2lbs of shock it will be fine. After reading the SLAM method it seems that I would need to keep shocking the pool until the chlorine stays steady.

Any thoughts on my PH questions?

 

[ajw22]

Please post only your Taylor kit tests. That is what we all use do we have a common reference.

Your TA is around 100. That is the reason your ph rises rapidly.

Let your TA settle around 60 and your pH will be more stable.

When your pH gets into the 8s lower it yo 7.4-7.6. Over time it will lower your TA,

Stop using your tabs and chlorinate with liquid chlorine. The tabs are adding acid which keeps you from knowing what is happening to uour pH.

Do not add any chemicals to raise your TA.

 

[Newdude]

Considering all the tests I've done, is the Taylor dot test the most accurate?

Yes. And you need to pick one method/kit and stay with it. Multiple sources or directions is a recipe for disaster.

So I'm wondering how I get there without overshooting the mark.

Add 15 ppm of granuals dosing per the Taylor kit and PoolMath, instead of waiting for the tabs to slowly raise it a little at a time. Wait for it to register in a day or two and reassess.

Do I need to shock the pool more to have the chlorine stabilize?

Chlorine is stabilized by CYA and depleted by organics or UV from the sun. Get the FC protected with 30 or 40 CYA. Then we address any organics if present from having such a low FC repeatedly.

The combined chlorine is not too bad,

You need FC, in order to create CCs. If your FC is .5 or 1, there's no chlorine left to make CCs. Think if it as a pie. If you have a whole pie, you can eat 4 slices. If you have one slice left, you can't eat 4 slices. So saying you didn't eat 4 slices today doesn't really tell the story if you didn't have the ability to in the first place.

After reading the SLAM method it seems that I would need to keep shocking the pool until the chlorine stays steady.

SLAM is maintaining a FC that's 40% of your CYA level to kill off any organics depleting your FC, after your CYA is raised to 30. Or else the FC will be depleted by the sun and the organics (if present) will remain.

 

[ajw22]

What is the pH and TA of your fill water?

 

[BMerrill]

The CYA test is the most subjective, but the readings on the scale are logarithm not linear so interpretations between the scale is not accurate.
It is recommend to fill the tube to say the 100 line. Do a quick glance not a stare. See the DOT? fill the tube to the next line repeat until you no longer see the do at a quick glance. This is the value to report.

More info and helpful hints can be found here.

 

[EastCoastDigs]

Thank you all for your helpful responses. I've just tested the water with the Taylor K1005 for today. Here are the results:

FC: 0.5
TC: 1.0
PH: 8.2-8.3
ALK: 110
CH: 330-350
CYA: under 20

Last night I added some CH to bring that up a bit (which is why it's higher today than in my original post).
Today, after testing, I've added Muriatic Acid to bring down PH (about 38 oz). I can retest later today to see how that's dropped. In the meantime, I plan to:

1. Add more liquid stabilizer today: I heard from Newdude that I should start with adding 15ppm, does that still seem right?
2. Then tonight, I can add more Cal-Hypo 73, how much is suggested?

From now on, as PH rises, I will continue to lower the PH with Muriatic Acid until it comes down to 7.4 - 7.6, and I'll see where my TA is then. What I'm getting from the forum here is, eventually, my TA will be low enough that it keep my PH stable.

 

[ajw22]

Your CH is fine at 300-350. I would not add more calcium or use cal-hypo which will raise it further.

Get your CYA up to 30-40 and focus on your FC and pH.

 

[Newdude]

1. Add more liquid stabilizer today: I heard from Newdude that I should start with adding 15ppm, does that still seem right?

Liquid is tricky if not using the full jug. The goods clump on the bottom and you pour mostly water out. Then a chunk of sludge oozes out and you overshoot on the 2nd or 3rd attempt.

The rec for 15 was due to the reading at 20 or below. It will get you near enough to 30, to reassess at that time.

2. Then tonight, I can add more Cal-Hypo 73, how much is suggested?

You need FC and pronto. You don't want to be gifted a swamp before the CYA gets to work. Use high target for 20CYA

What I'm getting from the forum here is, eventually, my TA will be low enough that it keep my PH stable.

Yes. Maintain the PH in the 7s and the TA will find it's happy spot. 60 to 100 is 'in range'

 

[proavia]

How old are the reagents in your Taylor K-1005 kit?
Has the kit been stored inside the house when not in active use?

If the reagents are more than a year or so old or the kit wasn't stored indoors, consider replacing with a TF-Pro test kit. The TF-Pro contains the needed FAS-DPD chlorine test and the SmartStir. At a minimum, get new reagents and a Taylor K-1515 (FAS-DPD -- let's you accurately test FC up to50 ppm).

The ColorQ products may be okay for quick checks once everything is in balance, but always use the drop based tests for accuracy. The ColorQ has been known to be off - especially in the CH test.

Don't bother with comparing to pool store tests. Pool store testing has proven to be inaccurate and will only confuse you more.

Liquid CYA is expensive and if you don't use the entire jug it will not provide the expected CYA increase. Using granular stabilizer is more economical and only takes a day or two longer to register when using the sock method for adding it.

 

[EastCoastDigs]

Thanks, proavia. I get fresh reagents for all my kits yearly from a reputable source, and I store them appropriately.

 

[EastCoastDigs]

Okay, so the update for today. After putting in about 38 oz of Muriatic Acid 24 hours ago. My PH is in the same spot, it did not go down, if it did it bounced back up within 24 hours. It's back at an 8-8.1. My AK is down to 100. Do I just keep adding Muriatic Acid, should I double the amount?

Separately, what is the cadence for adding liquid bleach to maintain FC levels? I know this is going to depend on the size of the pool, and location, among many other factors, but how often are we finding we need to add it? Once a week, a few times a week? Do you generally find a cadence to it without having to check your levels daily?

I'm at a FC and TC of 3 right now with my CYA now at about 35.

 

[Newdude]

My PH is in the same spot, it did not go down, if it did it bounced back up within 24 hours

Did you verify it did what you expected after dosing ? With high/low PH, it may be further out of range than the color appears. When it's not a 7, you need to check 15 mins after dosing/mixing. Repeat dose/test as necessary.

Do you generally find a cadence to it without having to check your levels daily?

Yes. But you need to get to know your pool and how it responds throughout the season first. After a while you'll expect the FC to be a X when you test it, and you'll be right or darn close more often than not. Then, because you have a feel for it, you can double dose and skip the in-between day. (Verifying the first day that it works until the second day). Fine tune as necessary.

It's ironic that a little more work now Makes for much less work later. And it becomes second nature QUICK. Most don't even mind it at that point.

I hated the going and getting the jugs. Testing and dosing is cake once the jugs are on site.

 

[EastCoastDigs]

Good point, I guess I will add some more MA and then test again to see what happens.