Water test Results

[FNC1962]

Few of us ever shock our pools unless we become aware of an incipient or active algae outbreak. We use plain 6% regular household bleach as sanitizing agent, adding an appropriate amount daily after testing for FC, CC, and pH. Water in balance that's properly maintained requires neither "shock" nor algicides.

Now, your test results:
FC = 18.2 – as Janet stated, that will drift down by itself. You want to maintain it between 3 ppm (never lower) and 6 ppm. When you test, you do NOT need to use a 25 ml sample. You can use 10 ml pool water, a heaping dipper of DPD powder, and multiply the drops you've counted by 0.5 to get the ppm.
CYA = 42 – Is the number 42 an actual line on the comparator? Anything between 30 - 50 is okay though we see the best results with CYA nearer to 50 ppm.
TA = 70 – that's okay but a little low. You might get better pH buffering with TA around 100. Get some Arm&Hammer baking soda, a large bag, in the baking aisle of your grocery store. Add 3 cups of baking soda. You can add it to the skimmer while the pump is running or in front of the return. Keep the water circulating so the baking soda mixes in, then test after 3 hours or so. You'll like be in the 80s somewhere. Add 3 more cups.
pH = 7.0 – that's a bit low. It will go up somewhat with the addition of baking soda, so I wouldn't do anything with the pH just now. While you're out buying baking soda also pick up some 20 Mule Team borax in the laundry aisle. We may need that to fine tune the pH later.
As to pH testing, when the FC (chlorine) is over 10 ppm the pH test is not valid. Let's let the FC drift down below 10 ppm and then deal with pH. You do NOT add more drops to get a better/different color. The chemicals are calibrated for five drops and what you see is what you have.

While you're out shopping pick up some bleach. Plain, unscented, un-gel'd, just bleach. That will be your daily sanitizer and your "shock" and your algicide.

Okay, My FC is now down to 5.5. CC 0.5 , TA is at 80, PH 7.1 (took 3 drops R-0006 to get to 7.6) Whats next on my to do list? I did pick up some Borax

[AnnaK]

Add 3 more cups of baking soda to raise the TA a little more. Let that mix in and circulate for an hour, then add 2 cups of borax. My best guess is that your TA will then be in the 90s somewhere and the pH around 7.4/7.5

The CC of .5 is okay but we'd rather have it at zero.

From here on you test daily for FC, CC, and pH. You add enough bleach to keep the FC between 3 and 6 ppm. This is based on your reported CYA of 40-something. In your pool, 1/2 gallon of 6% bleach will add approximately 5 ppm of FC. You should be okay with adding 1 quart of 6% bleach every evening, depending on the swimmer load that day. Test the water in the evening. It's going to be a little bit of trial and error and we want to err on the high side. You will soon get to know your pool and develop a 'feel' for what it needs.

[FNC1962]

Add 3 more cups of baking soda to raise the TA a little more. Let that mix in and circulate for an hour, then add 2 cups of borax. My best guess is that your TA will then be in the 90s somewhere and the pH around 7.4/7.5

The CC of .5 is okay but we'd rather have it at zero.

From here on you test daily for FC, CC, and pH. You add enough bleach to keep the FC between 3 and 6 ppm. This is based on your reported CYA of 40-something. In your pool, 1/2 gallon of 6% bleach will add approximately 5 ppm of FC. You should be okay with adding 1 quart of 6% bleach every evening, depending on the swimmer load that day. Test the water in the evening. It's going to be a little bit of trial and error and we want to err on the high side. You will soon get to know your pool and develop a 'feel' for what it needs.

Okay, my evening test result after adding baking soda and borax are FC 4.0, CC 0, TA 90, PH 7.3 Cya 60. I am going to add a quart of 6% bleach. Do I need to add more Borax and/or baking soda? Thanks
Frank

[aylad]

Go ahead and add your bleach--your pH and alk look fine to me.

Janet

[AnnaK]

It's looking great, Frank!

Try to keep the FC between 3 and 6 ppm, test FC, CC, pH daily, add bleach as needed. Are you keeping a pool log? I use a notebook in which I write test results, type and amount of chemicals added, when I backwash/rinse, that sort of thing.

The log can sometimes be your first clue of trouble, before you see or feel problems with the water, and can teach you to be proactive. At closing and opening you can refer back to previous years to see what you did and, if a problem comes up during the season, you can look back to see how you dealt with something similar in the past. It's also a good place to track money spent on pool related items.

Enjoy your pool, you've worked hard to get it where it is.

[FNC1962]

Great idea about the pool log. I will start doing this. How about my pH level, should I work on getting it a little higher? How often should I do the other tests?
Thank You very much for your advice, this forum is fantastic.

[AnnaK]

Your pH at 7.3 is fine. I suspect you want to raise it a little just because you know you can

Don't allow yourself to fall into the trap of "chasing numbers". That's where we get some magic value into our heads and think we have to reach that or the sky will fall, or something. Keep in mind that chemical levels in a balanced pool are in ranges: FC between 3 and 6 ppm, CYA between 30 and 50 ppm, pH between 7.2 and 7.8, TA between 70 and 120 ppm.

Watch your pH. Most pools like to stay at a certain level. As long as that level is within the above range, why fix something that isn't broken? If yours develops a tendency to drift up or down or if it drops below 7.2, then let us know and we'll help you figure out what's happening. With a TA of 90 you have a well buffered solution now which should keep the pH stable.

I test TA once a month unless my pH goes squirrelly for 2 days in a row. Then I test TA and adjust, if needed. I keep a relatively low TA because my fill water is low in alkalinity. Since my pool's pH is steady and I've not observed any corrosion issues I've opted to not mess with the TA . . . to not "chase numbers".

I test CYA four times during the season: 1. at startup, 2. after adding enough stabilizer to reach 50 ppm during startup, 3. at the end of July, to see how much I've lost from splashout and refilling, and 4. at closing.

I have never done an acid demand test or a base demand test.

There's some hot weather in the works. Go swim!