Pool will not hold chlorine

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You can do that testing to start. Eventually you will learn your pools needs.

My pool with cya of 80 requires 1 gallon of bleach every 3 days to maintain. (not including guests being over that consumes more)

For example, it might sound crazy but I only test chlorine levels in the swimming warmer months about every 2-3 days.
But I do test it every day I have guests over because that can drop my FC by 5 or 6 a few hours after they leave.

PH I only test once a month because my pool somehow the PH always stays the same constant 7.5 (some pools ph constantly rise, some lower some stay level like mine.

All the other tests I only do once a month. and every time I do the levels are the same for TA, CH & PH


use the pool math calculator to figure out the pools needs.

In the winter I keep my pool open. When it gets near 55 degrees and stays there and goes lower, I up my chlorine to 25 ppm and there it
stays without needing to add chlorine (nothing in the water alive to consume it) until the spring comes and warms the water to 60 degrees.
 
Okay, yesterday was the test where we were holding our FC level at 17.5. Since yesterday we have added nothing at all to the pool letting the free chlorine drop down. And here are our readings now.

FC 6
CC 0
TC 6
CH 200
TA 90
PH 7.5 maybe 7.6

So to us it looks like everything is pretty good except the CH at 200. The kit says it should be between 250-400. But on the recommended levels I read on this site it says 0-350. So which level range is correct? And if we need to raise it, what do we use?

Also, for the TA, our reading is 90. The chart in the test kit says between 100-120 for manually chlorinated pools. And the recommendation on this site says 70-90+ so what should our ideal range be?

When I have to raise my PH, can I still use my soda ash because I have a brand new 50 pound bag? And when raising the TA and the CH, what do we use?

Thank you!
 
Wow! Thanks, Jason. That feels great! And yes, we are going to use the TFPC method. So far it seems to be going way better than when we were running to the pool store and blowing through money with no good results. You guys are awesome! And I know we had a lot of questions. But it was a lot to take in at the beginning and we didn't want to screw up and make it worse by doing things the wrong way. So now we will just try to maintain our numbers and enjoy our pool this summer.
 
Okay. Question for you. Yesterday at 9:30 a.m. our FC was 3.5. CC was 0. We added 2 quarts and 2 cups because we couldn't get on the site yesterday so just used amounts from previous additions to pool. Checked FC again about an 1 1/2 later at 11:00 a.m. and it went to 7.5. At 9:30 p.m. we checked it again and FC was at 4.5. Added 2 quarts and 2 cups of bleach. Checked FC again about an hour later at 10:30 p.m. and FC went up to 8.5. A little higher than we were shooting for, but okay. Then today at 7:00 a.m. we checked the FC and it was at 6. Is it okay that it went down so much overnight? We weren't doing an OCLT test, just monitoring our chlorine use. I want to make sure I am understanding all this. Should the pool be using 2.5 ppm over night? Is this different than when doing a OCLT test?
Thank you!
 
It is only and OCLT if you test at night after swimming and the sun is off the pool and you test in the morning before the sun hits the pool. If that happened then 2.5 is too much. If there was a lot of swimming yesterday afternoon/evening then maybe not.

Here is the process to http://www.troublefreepool.com/content/136-perform-the-overnight-fc-chlorine-loss-test-oclt. Take FC up to about 10 for this.

And good job working on understanding your chlorine usage. I like it! :goodjob:
 
Thanks! I'm working on understanding, but still have a ways to go. But I'm really trying to learn it all!

So last night the test was done at 9:30 at night, so it was dark. Then added the bleach. I tested again an hour later at 10:30 p.m. FC was at 8.5. Bill got up this morning at 7:00 a.m. and FC was at 6.0. He added 1 quart and 1 cup bleach. He did not check after adding because he had to go to work and I didn't know he had done anything until later. Not sure if the sun was on the pool by that time or not. And there was no swimming at all yesterday in the pool. So it seems like it lost 2.5 ppm overnight. The pool is very clear and looks great. So I tested again at 4:00 p.m. today and FC was still at 6.0 like it was at 7:00 a.m. after he had added the bleach. So I didn't add anything. I just tested again at 8:30 and FC is at 8.0. So it's weird that it's going up as the day goes on today. Maybe it's just taking a while for it to all get mixed up. So I don't think I will add anything tonight and will check again in the morning and see where we are at. It's just a little confusing. :confused: And the pool was not used at all today either. Hope I can get this figured out.
 
That makes me suspect the test this morning. Either not mixed in, odd sample for some reason or sleepy testing. I think the sun is up at 7:00, but I'm not trying too hard to pay attention to that!
 

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Probably the usual suspect, for sure...haha. I checked the pool one more time at 10:30 p.m. last night. FC was 5.5. Added nothing and then this morning checked at 6:00 a.m. and it was FC 5. Added 52 oz per poolmath. Waited and checked it at 9:00 p.m. tonight. FC was at 4. So I just added 62 oz per poolmath and will see what it brought the FC level up to and then check again in the morning. Wowsa....
 
I must be wrong on the gallons in my pool. Last night at 10:15 p.m. my FC was at 5.5. Today at 9:00 a.m. my FC was still 5.5. Great.

But at 9:00 p.m. tonight I checked FC and it was at 3.0. So I added 107 oz of bleach per pool math shooting for FC of 7.0. But it only brought it up to 6.5 ppm. So I'm going to have to figure out how to get the gallons for my pool correct so the pool math calculator gives me the correct amounts. Anyone know how to figure how many gallons from what happened with my last addition tonight? Maybe 18,500 gallons or 19,000 gallons?
 
The amount of FC can vary based on the age of the chlorine. If all adjustments to your pool always seem to confirm you have more water, try using the estimated effects using the Pool Math calculator and increase the amount of water at the top until the estimates of adding chemicals match your measurements.
 
jstblush said:
I must be wrong on the gallons in my pool. Last night at 10:15 p.m. my FC was at 5.5. Today at 9:00 a.m. my FC was still 5.5. Great.

But at 9:00 p.m. tonight I checked FC and it was at 3.0. So I added 107 oz of bleach per pool math shooting for FC of 7.0. But it only brought it up to 6.5 ppm. So I'm going to have to figure out how to get the gallons for my pool correct so the pool math calculator gives me the correct amounts. Anyone know how to figure how many gallons from what happened with my last addition tonight? Maybe 18,500 gallons or 19,000 gallons?
Click to expand...

It is my understanding, the accuracy of the FC testing (w/10ml water sample), given it is done correctly, is 1/2 ppm (not sure if this is +/- 0.5ppm or +/- 0.25 ppm but will use +/- 0.25 ppm for what follows). Taking the difference of two measurements with an accuracy of +/- 0.25 ppm gives a variability of the difference of +/- 0.5 ppm. Don't worry if the difference of your prediction and measurement are off by less than 0.5 ppm since the first FC, in your case 3 implies a actual FC of 2.75 or 3.25 and your result of 6.5 could actually be 6.25 or 6.75. Therefore your actual increase ranges from 3.0 (6.25 - 3.25) to 4.0 (6.75 - 2.75). Therefore, the result that you were trying for is within the range of possibilities based upon the measurement accuracy of the test.


Gary
 
Thanks guys. It was about 105 degrees out yesterday and there were 4 of us using the pool for a couple hours.

Started the day at 5.5 FC and it was down to 3.0 by 9:00 p.m. Added 107 oz shooting for 7.0 and checked it an hour later at 9:00 p.m. and it was 6.5 like I said. Then this morning checked it at 8:00 a.m. and it was at 8.0. I am guessing that the higher reading in the morning is higher because the bleach is all mixed up by then. I'm not sure. But it makes it a little confusing when you check it at night and in the morning the reading is higher. And that's way after the sun has come up and been on the water. I guess I'll just be happy that we are holding FC now since when we first came to this site, we couldn't hold any. But it makes me wonder if the OCLT reading is correct if it's taking that long to read the actual FC. Sorry to be a pain, but just confused by it. :confused:

But don't get me wrong. The pool is sparkling and beautiful and holding chlorine so we are happy!
 
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