Got my new TF-100 Bundle over the weekend. Got a few questions

[Aubie99]

Hello All,

Apologize in advance for long post. Question starts at start of test results.

So I got the new TF-100 bundle startup kit in over the weekend and have been playing with it. First off, let me give a review of the process, items, and response from Rebecca at TFTestkits because it was awesome:

• Ordered on Wednesday evening when I got home (~6pm'ish).
• Immediate response auto generated with order# I assume
• Follow up email from Rebecca early 30 on Thursday morning with shipping/tracking info
• I made donation on Thursday to support forum and didn't realize I received a discount for test kit.
• Sent email to Rebecca and she responded within an hour and credited me the amount of discount back
• Package arrives Saturday (didn't think I would receive until today...nice surprise from USPS)

Review of items received:

• Whale Wall Brush - amazing product...can't believe brushing could be so easy. Get one if you don't have one.
• Skimmer Angel - the SO's amazing product. Get one if you don't like sticking your hands to pull skimmer basket out for cleaning. Now SO can clean skimmer basket when I'm not here. Well worth it.
• Taylor Speed Stir - sweet little product that makes the titrations a breeze (just like chem lab). Must have in my opinion if you titrate your water chemistry.
• TF-100 test kit - neatly arranged kit with all necessities for testing filled with info and laminated test direction card.

Awesome products for a great price and you can't beat the customer service from Rebecca (wish it could always be this easy to deal with someone).

Now to a few questions (it could be my technique as it has been a while from my chemistry testing days in school). First test results (water crystal clear):

• pH - 7.8
• FC - 17.0 (coming down from SLAM after vacay...no test kit, so I swag'd it)
• CC - 0.0
• CYA - 70
• Salt - 3200
• TA - 200
• CH - 100

I ran a duplicate to verify my test methods and came up with same results. I know the pH can be skewed to high side with higher FC readings, but I was surprised at the TA number (didn't think it was that high based off my Aquacheck strips I had been using) and figured I would add recommended dosage of MA to get it down. Added 29oz I believe to bring pH down some and then give it overnight to see what happens and get a retest next day. Also turned SWG back from 75-10% to allow FC to start working down now that I had my test kit (didn't turn it completely off due to Father's Day party and many people/kids in pool following day). Following afternoon results:

• pH - 7.5
• FC - 13.0
• CC - 0.0
• CYA - not tested
• Salt - not tested
• TA - 90
• CH - not tested

Question: Is it reasonable to expect the TA to drop that much with little aeration (well maybe kids splashing and playing) in the pool and only that small amount of MA added? I re-ran the test in duplicate just to make sure results were ok. Test were grabbed from same location in the pool and the pool pump/Polaris was allowed to run all night after the party. All test look good and FC continues to creep down, will adjust SWG back up when I get the FC/CYA target. Thanks for the help

 

[borjis]

Your probably ok on the TA.

I had accidentally put in too much baking soda last time
and it sat at 90 for few months but didn't affect the ph
much if at all.

It has drifted to 80 now (tested last saturday) likely
due to a few rains/draining of excess water.

YEs important to test always in the same area,
and about 1 foot below in the deep end.
(I use a dedicated turkey baster to sample)

 

[Aubie99]

Thanks borjis. Yes, I'm happy with the TA at 90 as that was where I wanted to get to, but with that high of TA in first place and not much MA added, I wouldn't have thought it would have came down that much.

 

[basod]

It's likely a variability in your testing of the TA.
on new chemicals follow the "wipe tip between each drop" directions when adding final developer.
You will likely see a vortex of red forming if using the speedstir, allow it to dissipate before adding each additional drop

 

[Teald024]

Added 29oz I believe to bring pH down
Question: Is it reasonable to expect the TA to drop (200->80) that much with little aeration (well maybe kids splashing and playing) in the pool and only that small amount of MA added? I re-ran the test in duplicate just to make sure results were ok. Test were grabbed from same location in the pool and the pool pump/Polaris was allowed to run all night after the party.

Hello and Welcome to TFP!!

To answer your question, no it's not reasonable. The TA drop happens when you add the acid not when you aerate. Adding 29oz of acid would only drop your TA by less than 10ppm. It would take a number of iterations to get TA from 200 down to 80.
You aerate to get the pH up. You then add acid to get pH down and doing so drops the TA.

 

[Aubie99]

Ok, thanks for the info. I'm going to run some more test with the "wipe tip between drops" method basod recommended. I guess my first testing could have been way off based on above info.

 

[Aubie99]

Retested TA and still showing 90 with wiping dropper after each drop. Looks like my first tests were probably bad results. Thanks for the help

 

[Teald024]

Added 29oz I believe to bring pH down
Question: Is it reasonable to expect the TA to drop (200->80) that much with little aeration (well maybe kids splashing and playing) in the pool and only that small amount of MA added? I re-ran the test in duplicate just to make sure results were ok. Test were grabbed from same location in the pool and the pool pump/Polaris was allowed to run all night after the party.

Hello and Welcome to TFP!!

To answer your question, no it's not reasonable. The TA drop happens when you add the acid not when you aerate. Adding 29oz of acid would only drop your TA by less than 10ppm. It would take a number of iterations to get TA from 200 down to 80.
You aerate to get the pH up. You then add acid to get pH down and doing so drops the TA.

Retested TA and still showing 90 with wiping dropper after each drop. Looks like my first tests were probably bad results. Thanks for the help

I just thought of something. What water volume are you using now, how many drops, and what multiplier are you using? The difference between 200 --> 80 is 2.5x

That happens to be the difference in multiplier for a lot of tests. 25ml vs 10ml. Multiply drops by 25 or by 10. Could this the cause of the error?

 

[Aubie99]

I was using 25mL sample of water for all tests (so multiplying by 10). 9 drops now as compared to 20 drops on first test with kit. I was holding titrant vertically on all tests but not wiping between drops on the first set. One thing I did notice thinking back was the drops on first test seemed to come out quicker and smaller (they are now creating a larger drop at end of dropper before they release into graduated cylinder).