1st Sample Testing Using TF Test Kit - Questions

[swanny297]

Hey gang

I did my first water tests using the TF test kit this morning and have some questions, here are my results, pool is very clear and looks great.
FC - 5.5 (CH drop test)
CC - 0
TC - 5.5
pH - 8.0 (difficult to detect using colors for me)
TA - 270 (did the test twice, 260 the first time, 270 the second)
Salt - 3000ppm on the controller - 2640 Aqua Check Strip (2 tests)
I did not have time to do CYA because I was concerned about the TA test.

So - I take a sample to the local pool place (where I have been getting my water tested).
FC - 2.2
CC - 0
TC - 2.2
pH - 8.7
TA - 146
CYA - 88
Salt - 3000ppm

When I looked at the top of the test print out it states 19,400 gals - pool - printed vinyl. When I use the pool calculator and the water depth measurements I tooI get 17,500 gallons. So there test results are assuming about 2000 more gallons than what I have (I am going to measure exact today the dimensions of my 27ft round pool). The pool place uses a bioguard tester. I would guess that since they are using a larger volume of water it would dilute my results a little if the water volume is some how factored into the calculations. I am going to test again tonight - but if my TA is that high, do I just need to add muriatic acid to get the pH down to about 7.1, and allow it to rise, and do again until I get my TA down? I know a few more times with my test kit I will feel more comfortable, but I am concerned about the differences in TA and hoping water volume is the culprit.

Thanks
Clint

 

[JasonLion]

The volume of the pool has nothing to do with test results. Your water test results are all in units of chemical per unit volume of water, so it doesn't matter what size the pool is. The size of the pool enters in when you try to calculate how much chemical to add. So it is good to know the size of your pool, but it doesn't affect your test results.

Seeing significant differences between your test results and the pool store results is common. Pool stores are all too often amazingly bad at water testing.

Do the TA test again, but this time wipe the tip of the dropper bottle with a damp tissue every couple of drops.

Your PH and TA are both high either way, though not as dramatically if you believe the pool store (which I don't). So you should lower the PH to around 7.2 regardless.

 

[frogabog]

I would be less concerned about TA at the moment and more concerned about the chlorine. Both results show that the chlorine is low. For CYA of 88 you should have no less than 7ppm, with a high target of 12ppm daily. Now is the time to do your own CYA test. Re-pour it a few times and use the most consistent result you see. Back to the sun, hold at waist level. Fill the tube till the dot is completely gone.

PH should be addressed right away as well. Each time you lower pH with acid, the TA will come down a bit too so expect to do this a few times before things settle out.

 

[swanny297]

Frogabog - According to the SWG CYA/Chlorine chart in the pool school my chlorine should be min 4 target 6 (for a CYA of 80) - if my test is correct than I am in the range???? The values you have appear to be for Chlorine pools (at least according to the chart).

I am going to do all the tests again tonight - I printed off the Extended test kit directions, I noticed in the FC test it is OK to add a little too much R-0870 powder - I don't think I added enough, I don't remember seeing any undissolved crystals in the bottom.

Thanks for the feedback.

 

[frogabog]

oops! I didn't read your sig properly. Yes, you're right.

I think your chlorine must have degraded some on the ride to the store. Regardless, your tests are the ones you should rely on. Their stuff seems fancy and cool but it's way too often completely off like you're seeing.

 

[swanny297]

2nd TF Test vs Pool Place - Need Help

Alright gang - I have performed my second test today using the TF test kit, here are the results:

FC - 1.5
TA - 190
CYA - 0 (I could see the dot with the tube full)
pH - 7.8-8.2
Salt - 2860 aqua rite test strip (controller is reading 2800)

Here are the results from the pool place this AM -
FC - 2.2
CC - 0
TC - 2.2
pH - 8.7
TA - 146
CYA - 88
Salt - 3000ppm

My main question is what should I go after first CYA? I have muriatic acid to lower the pH and start on the TA. I don't have anything for CYA - I do have a little bleach that I could use for FC - we are expecting the tip of a tropical storm so we will probably get some rain tonight or tomorrow. I can still make it to lowes or home depot if I need to. What is the best for CYA keeping in mind I have an AGP and SWG. I will use the pool calculator figure out how much of everything just need some help as to order if it matters pool water is clear we just finished swimming:

Lower pH, Lower TA, Increase salt, Increase FC, Increase CYA

Thanks
Clint

 

[frogabog]

Re: 2nd TF Test vs Pool Place - Need Help

Something's not right with the CYA. You mixed it for 30+ seconds right? Was your mixture 1:1?

I took a peek at your history and it looks like you've used shock product powder in the past. Was that dichlor shock product? If so, or if you've used tablets at all your CYA can't be 0. All your pool store results posted here show CYA above 74, and then it rose again after you used the shock product (it seems). I would be very very sure of the CYA value being 0 before you add CYA. If there was a testing error, and you're really very close to 90 you will not want to add any CYA.

Question is... how much CYA do you think your pool should have right now based on what you've used to chlorinate or shock since filling?

 

[swanny297]

Re: 2nd TF Test vs Pool Place - Need Help

I just talked with my installer and he did not add anything to have a CYA reading - I have only had to add 2lbs of shock, so he feels the reading of 88 by the pool place is not accurate since we have not added anything that would increase CYA levels. So I guess I need to start out adding a little bit to bring it up to a certain level and measure before I add too much. The installer said my CYA level should be around 0. I am going to test again, but I tested 3 times following the procedure in the TF test kit and got 0 each time.

Thoughts....

 

[frogabog]

Re: 2nd TF Test vs Pool Place - Need Help

What was the shock product you added?

I agree however with the PB, 2 pounds of dichlor would not leave you with a CYA of any measurable value. Far less than 20ppm for sure.

I would pretend that 10ppm might be in the pool if the shock product was dichlor and add 60ppm CYA. If it was not dichlor, then go with 0ppm CYA and use the calculator to add enough to get you to 70ppm and then wait a week to test. Assume the CYA is in the pool and at the value you intended it to be once it's all dissolved from the sock (squish squish squish it frequently by hand).

You can adjust the pH and chlorine while the sock is hanging. Just guestimate the CYA level as it reduces from the sock and raise chlorine accordingly (i.e. if half the CYA has dissolved, assume 50% of your intended CYA value is in the pool and chlorinate for that value). Once it's all dissolved the SWG should work much better, and at a lower setting.

 

[swanny297]

Re: 2nd TF Test vs Pool Place - Need Help

I am guessing I need to go to a pool store to get CYA? When you mention a sock, do I just put it in a sock and add it to the skimmer? How expensive is the liquid stabalizer if I went that way I know I would need 3 gallons if I assume I am 10ppm - and do you just dump it all in at once in front of the return jet?

Thanks

 

[frogabog]

Re: 2nd TF Test vs Pool Place - Need Help

The solid stabilizer is less expensive, and dissolves fast enough for your purpose. If you can find HTH brand (try walmart) it'll dissolve within a few hours of the squishing process. The pool store brands can tend to be more... solid and take longer to dissolve but either works just fine. The liquid is your choice to choose, but not usually necessary or beneficial enough to justify the expense.

Yes, put it into a sock, tie the top with a rubber band and then tie it off to hang in front of your return so the water flows around/past/through it. Or hang it off the ladder. Hand squishing makes it dissolve much faster than if you don't squish it. If you put it into the skimmer (without a sock) you won't be able to clean the filter till it's all dissolved (that can take a week). Sock squishing works much better.