Review of my results please

MaxAcceleration

LifeTime Supporter
Aug 29, 2012
33
Caledonia, IL
Pool Size
24000
Surface
Vinyl
Chlorine
Liquid Chlorine
FC = 4.5
CC = < .5
Ph = 7.5
Alk = 150
CYA= 20

So things are looking much better with my pool this year. Last year I had a CYA of 120 (yikes!) and a partial refill during the winter closing did the trick.

I feel I have a good grasp on what I'm doing now. My water has never looked better I've even trained another person on using the BBB method and finding that training others really reinforces what I've learned here. A big thank you to everybody!

That said I do have a few questions:

1. My current usage is about one gallon of 12.5% bleach a day which I buy from the pool store for $11.30 for a case of four. With tax that's roughly $3 a bottle. So that's $90 a month ($450 for five months) in chemical usage to run the pool and I'm wondering if that's good, bad or indifferent compared to others with a similar pool size (25k gallons)? This does not include any extra I'd need if I have to shock again.

2. My plan is to get my CYA to 30 by using some pucks. Should I test daily, weekly, bi-weekly for CYA? ie... how long will it take for pucks to move my pool from 20 to 30? and when I say 20 I'm guessing because I fill the entire tube up and can still see the black dot. However I only drained half the pool last year with a cya of 120 so there should be still some in there.

3. I understand the cya chlorine relationship, but if somebody has a high CYA and requires a higher range of bleach, I've read on TFP that it is safe to swim in all the way up to shock level, which could be 39ppm in some instances where cya is over 100. Is this still true and how can it not hurt you at that level? I'm asking as that was one answer I didn't know how to explain to somebody.

4. Being I have a sand filter I wanted to see what adding DE would do for me. With my water clear, I followed the procedure here: http://www.troublefreepool.com/pool-school/add_de_to_a_sand_filter and at first was able to get two cups in. About 3 hours later the heater turned off from low pressure and the pump was working hard so I did a backwash and noticed quite a bit of dirty water. So I lowered it down to one cup and it did about the same this time but not as much dirt. So I went down to 1/4 cup and it did the same after about 5 hours again without much visible dirt during the backwash. So my question is am I doing this right? I changed my sand out this year, inspected my laterals and refilled with new pool grade sand so I know the sand filter itself is good. Any recommendations?

Thanks again,
Jamie
 
I think you will be able to use less liquid per day if your CYA is raised to 50. The average daily loss of FC is in the area of 2-4 ppm (varies depending on a number of factors) so if you are going through more than that a day you should verify why. Is your FC holding overnight?

You can see how much the tablet raises it by using the "Effects of Adding Chemicals" section of the Pool Calc. Put "7oz trichlor" as that is a rough estimate of the weight of the tablet. I would test CYA every 2 weeks if you are going through a lot of tablets.

The Chlorine is bound to the CYA - the CYA acts like a buffer. Somewhere there is a very detailed description by Chem Geek that give the scientific explanation ... I'll try to find it.

Yes you are doing the DE right - probably too much at first LOL but that's okay trial and error is a good way to learn, no harm no foul. The fact that its filtering better shows that perhaps something is going on which goes back to my earlier question - is your FC holding overnight?
 
MaxAcceleration said:
FC = 4.5
CC = < .5
Ph = 7.5
Alk = 150
CYA= 20

So things are looking much better with my pool this year. Last year I had a CYA of 120 (yikes!) and a partial refill during the winter closing did the trick.

I feel I have a good grasp on what I'm doing now. My water has never looked better I've even trained another person on using the BBB method and finding that training others really reinforces what I've learned here. A big thank you to everybody!

That said I do have a few questions:

1. My current usage is about one gallon of 12.5% bleach a day which I buy from the pool store for $11.30 for a case of four. With tax that's roughly $3 a bottle. So that's $90 a month ($450 for five months) in chemical usage to run the pool and I'm wondering if that's good, bad or indifferent compared to others with a similar pool size (25k gallons)? This does not include any extra I'd need if I have to shock again.
That works out to 5 ppm/day. That seems awful high. Does the pool get a lot of usage? Lots of sweaty, dirty children? If not, it sounds like the sun is taking more than its fair share and raising CYA a little will help. Which leads to...
2. My plan is to get my CYA to 30 by using some pucks. Should I test daily, weekly, bi-weekly for CYA? ie... how long will it take for pucks to move my pool from 20 to 30? and when I say 20 I'm guessing because I fill the entire tube up and can still see the black dot. However I only drained half the pool last year with a cya of 120 so there should be still some in there.
Pool Calculator can tell you how much CYA each 8 oz. puck will add. (It's 1.3 for your pool) so you can work backwards from there and see how many pounds/pucks you can add safely. How long depends on how long it takes them to dissolve. Be aware they also affect pH. See Effects of Adding Chemicals on Pool Calculator.
3. I understand the cya chlorine relationship, but if somebody has a high CYA and requires a higher range of bleach, I've read on TFP that it is safe to swim in all the way up to shock level, which could be 39ppm in some instances where cya is over 100. Is this still true and how can it not hurt you at that level? I'm asking as that was one answer I didn't know how to explain to somebody.
Yes, it is safe. Consider the FC to be active and reserve for want of a better term. With super high CYA, most of the FC is in reserve. 25FC@100CYA has less active FC than 10FC@0CYA. But who'd want to go swimming in that muck anyway? And who would try to shock at that CYA level?
4. Being I have a sand filter I wanted to see what adding DE would do for me. With my water clear, I followed the procedure here: http://www.troublefreepool.com/pool-school/add_de_to_a_sand_filter and at first was able to get two cups in. About 3 hours later the heater turned off from low pressure and the pump was working hard so I did a backwash and noticed quite a bit of dirty water. So I lowered it down to one cup and it did about the same this time but not as much dirt. So I went down to 1/4 cup and it did the same after about 5 hours again without much visible dirt during the backwash. So my question is am I doing this right? I changed my sand out this year, inspected my laterals and refilled with new pool grade sand so I know the sand filter itself is good. Any recommendations?

Thanks again,
Jamie
What's happening is that you're catching all the super fine stuff that gets through the sand filter. You did it right the first time. The later attempts shortchanged the amount of DE. Expect frequent overloading at first, then it should go longer between backwashes, and then finally you will have filtered anything bigger than 4 microns or so out and it will go almost as long as just plain sand between backwashes.
 
Thank you for your answers, I read them thoroughly. I didn't know to use the "Effects of Adding Chemicals" section to find out how many pucks to add to affect CYA, so thanks for that. Thanks for the confirmation of my DE results as well - it's comforting to know that what I'm experiencing is normal.

Ok, tonight I will do the OCLT to make sure I'm not losing any chlorine. I did one during my original opening and I was good.

Now that I look at it closer, I'm only required to add 62oz of chlorine each day (goal = 4ppm) but I've been adding the entire 128oz jug. But I've only doing that because each morning I end up with a FC of 1.5ppm. So looks like I'm losing about 5ppm a day (as Richard said).

No sweaty kids or anything like that and we've only swam once so far this year. I do have a 16mil solar blue solar cover on it, not sure if that makes a difference or not.

One other thing I noticed is I still have small amounts of "dust" I like to call it where the seams of the liner are that I haven't vacuumed out yet. Does that stuff have to go to waste or can I backwash it? I've tried both and don't really know if the sand filter catches it or not because it kinda disappears once I vacuum it.

I'll report back tomorrow with the results of the OCLT.
 
anonapersona said:
You have a cover on it and are losing 5 ppm of FC a day?

Yep I have a solar cover on it. My typical routine is wake up, check FC (usually at 1.5), add 128oz of 12% bleach, run the pump for 12 hours, go to bed. When I check the following morning it's back to 1.5. My CC is < .5 each morning. so I don't shock. That's without anybody swimming.

Now I do have to add that I recently added (about 10 days ago) the use of the solar cover and it was dirty from sitting outside during the Midwest winter. Is it possible the FC is cleaning up the dirt on the solar cover?

I'm going to do the OCLT tonight and see if I'm losing over 1ppm overnight and will post the result here in the morning.
 
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.