TF-100 Test Results

[Rancho Cost-a-Lotta]

I received my TF-100 kit and completed my first round of tests. Results:

FC - 6
CC - 0
PH- 7.5
TA - 100
CH - 800
CYA - 90-100

With the exception of CH, the results are pretty much what I expected. I performed the 10 ml CH test and stopped after 20 drops thinking I did something wrong. The second test took me to 32 drops before the sample turned from pink to blue. Third test showed the same results. I did not notice a "fading endpoint" as described in the Pool School section. I recently had my water tested three times at two different pool stores. Results were between 260-280. I know not to trust pools store tests, but the variance between my numbers and the pool stores' is significant. I followed the instructions included with the kit and at the Pool School closely so I'm perplexed. I recently installed a SWG and have been running it the last week. Prior to that for the two year life of the pool, my primary source of chlorine was pucks and powder shock, which explains my high level of CYA.

The CYA test was the hardest to read. I did the test with a full sample and ended up having to dilute. I would like to get a second set of eyes on the CYA test. My wife will be home tonight...how long can is the combined sample good for?

Water is clear with no signs of algae. I do have scaling at the waterline.

Any tips would be appreciated.

Mike.

 

[Richard320]

Better than I had when I took over. My CYA was over 200.

Your CH is not unexpected. We have hard water. When water evaporates, it leaves the CH behind. My pool gains about 25 ppm/ week during the summer. If you've been using Cal-hypo "shock," you're making it worse.

You can easily maintain the pool with super high CH. You just need to get the TA down to 50-70 brange and run the pH in the low end of the safe zone, say 7.2-7.5. That said.... 800 is about the practical limit.

Since you already need to replace some water to lower the CYA, you'll also lose some CH.

The CYA sample should be fine for a couple hours. Just make sure and shake it up good. Also, some people find it easier to fill to 30 and look, then 40, then 50, and so on. When they reach the point where the dot is gone, it ends up the same as if they'd dribbled the stuff in and rounded up.

 

[Rancho Cost-a-Lotta]

Thank you for the reply Richard. So if I drain about 20% of my water that would bring my cya within limits and lower my CH to about 640. Will that be okay assuming I run the lower pH ranges as you mentioned?

 

[Richard320]

Thank you for the reply Richard. So if I drain about 20% of my water that would bring my cya within limits and lower my CH to about 640. Will that be okay assuming I run the lower pH ranges as you mentioned?

Not exactly.... there's going to be some CH in the refill water. I'd overshoot a little now and then adjust salt and add CYA if needed. Then you can go a while before having to do it again. If you drain 20% and the refill water is 300 ppm. you'll be at 700 already.

 

[Rancho Cost-a-Lotta]

I reread your post. It'll probably be within the 25% to 30% range that I will need to drain. I will take a closer look at the numbers when I'm done with my outdoor chores.

 

[Rancho Cost-a-Lotta]

I have a few follow up questions. If I lower my PH 7.2, how much will my TA drop? Will that put me in the 50-70 range? If not, is it safe to drop below 7.2 and aerate to increase PH to safe level?

Do Borates have any effect on the CH test? I would assume not, but thought I would ask.

I'm 10-20 ppm above the recommended CYA level for a salt water pool. Is this something I can manage by maintaining the appropriate FC level?

I would REALLY like to avoid a partial drain.

Thanks again for the help!

 

[Richard320]

I have a few follow up questions. If I lower my PH 7.2, how much will my TA drop? Will that put me in the 50-70 range? If not, is it safe to drop below 7.2 and aerate to increase PH to safe level?

Plug numbers into poolmath and see what the acid dose should be. Then scroll down to Effects of Adding Chemicals and plug that in. It'll tell you what TA drop you should see. The pH calculation will be different, becauise it doesn;t take all the factors into account. TA will be real close.

Do Borates have any effect on the CH test? I would assume not, but thought I would ask.

No.

I'm 10-20 ppm above the recommended CYA level for a salt water pool. Is this something I can manage by maintaining the appropriate FC level?

Yes. Be aware that if you happen to develop algae, shock level will also go way up.

I would REALLY like to avoid a partial drain.

Thanks again for the help!

Understood. But you'll really need to watch the CSI calculation in poolmath lest you start growing Calcium scale. It's like grow-your-own sandpaper, and can cause roadrash on contact.

 

[Rancho Cost-a-Lotta]

Thanks for the help Richard. I dropped my PH to 7.3 overnight and saw a drop in TA. My current numbers show a CSI of -0.34. I will read up on lowering TA further.

 

[Richard320]

Thanks for the help Richard. I dropped my PH to 7.3 overnight and saw a drop in TA. My current numbers show a CSI of -0.34. I will read up on lowering TA further.

Don't make extra work. Just keep knocking the pH back to 7.2 when it reaches 7.8 and TA will go down by itself.

 

[Rancho Cost-a-Lotta]

Ok...but what am I gonna do with my time now?

Thanks again Richard. We'll see how everything goes.