chlorine consumption

[Brentlee98]

Hello,
New to forum. Built new inground pool last summer. Did a lot of research and thought I had mastered the art of maintaining a pool. No issues whatsoever for a whole year. Started using k-2006 test kit about a month into completion of pool after realizing that the strips were too vague. I keep pool open all year as I love being around the patio and the sheer descents. About 4-5 months ago, I stopped using pucks after gaining more knowledge of CYA. Since then, I have used liquid chlorine 10%. 4 months into it, my CYA had dropped from around 120ppm to 80 ppm. I was excited to see that I was on the right track. Here's the issue: within two weeks, my CYA dropped from 80 to around 0-10. I've dumped all kinds of chlorine in (liquid and pucks) and can barely get a reading of 0.6ppm chlorine. I've kept my pump running 24/7 for the past few days with the inline chlorinator set at max 5 (also adding a gallon of 10% chlorine daily). I've also added 5- 1 lb bags of shock (2 one day; 3 the next). Cannot get ppm over 0.6. What could be happening? How could CYA take so long to get from 120 to 80 and then crash to 0? Adding 1 gallon of chlorine used to raise 3 ppm. Now, an hour after adding, it doesn't even hardly register. Could my r-0870 dpd powder go back in a matter of a days? It did just expire 7/2017. I have a new one ordered and on it's way. Any other suggestions?

 

[pooldv]

Welcome to TFP!

Well, you solved the CYA problem. The FC must have dropped too low and there is bacteria consuming the CYA and converting it to ammonia which will eat up chlorine in minutes. Raise FC to 10 ppm and test in 15 minutes if FC is below 5 repeat until it holds at 7-10. Once it does add 30 ppm CYA in a sock and SLAM Process the pool.

 

[Catanzaro]

Brentlee:

Regarding CYA, this usually happens over the winter, but sometimes during the peak season. We have seen pools lose CYA during winter months. It could be ammonia. I have some information that shows how chlorine and CYA convert to ammonia, but will have to locate it. Try this first.

Sit by pool side and test every 15 minutes. Keep adding chlorine until you register a reading. If you register or when you register a reading, you have killed the ammonia. Again, just guessing at this point. With no CYA, you will not hold chlorine. You also may want to try this during the evening out of the sun.

 

[Brentlee98]

Thanks. I will try slamming this weekend when I have time to test throughout the day. I think the pucks are putting some CYA back in, as the last test a couple days ago was about 20, but still not holding chlorine at all. I'm thinking that I should have just left my CYA high and kept my chlorine levels at 8. I've had no troubles for one full year. BTW, PH is 7.4, TA 110, Calcium 300. My last reading of SI was near perfect 0 and I always try to keep it that way.

 

[Akathisia]

It wasn't normal for CYA to drop from 120 to 80 that fast without massive dilution, drain and refill or massive splashout, etc. Everything just accelerated after that.

 

[Brentlee98]

We've had massive amounts of rain this year. I'm sure I've pumped a good two ft of water out over the past 4-5 months.

 

[domct203]

Thanks. I will try slamming this weekend when I have time to test throughout the day. I think the pucks are putting some CYA back in, as the last test a couple days ago was about 20, but still not holding chlorine at all. I'm thinking that I should have just left my CYA high and kept my chlorine levels at 8. I've had no troubles for one full year. BTW, PH is 7.4, TA 110, Calcium 300. My last reading of SI was near perfect 0 and I always try to keep it that way.

Do not use pucks as they will add CYA, do not add CYA until you confirm if you have ammonia in the pool or not. Follow pooldv's post. If you do have bacteria converting CYA to ammonia, feeding it more CYA will just make more ammonia.

 

[Catanzaro]

I will try slamming this weekend when I have time to test throughout the day.

The process will take only a few hours. That is to get rid of ammonia and hold chlorine. Once you hold chlorine, then test for CYA. Add the appropriate amount to get to 30-40 as you will be removing water through backwashing. Then start your SLAM. Please keep us posted!

 

[Brentlee98]

Alright, just added 6 gallons of 10% chlorine in pool right now. How long should I wait until testing? Does it need to circulate first?

 

[mknauss]

15 minutes -- then test again.

As said previously --

Raise FC to 10 ppm and test in 15 minutes if FC is below 5 repeat until it holds at 7-10.

 

[Brentlee98]

Just checked and reading is 10.2ppm TC; 8.5ppm FC. Adding another gallon.

 

[mknauss]

Whoa -- read the note again - raise your FC to 10 with chlorine. You added 6 gallons for a FC of 24!

 

[Brentlee98]

I was already a couple steps ahead. Added 4 gals, then tested. FC was ~5ppm. Added 2 more, FC at 8.5ppm. Added one more, but waiting 15 minutes to test again. What am I missing that was incorrect? If I'm reading the post correctly, the ammonia eats the chlorine within minutes, which is why I'm not at 24ppm, correct?

 

[mknauss]

You add enough chlorine (calculated) to get to FC 10, wait 10 minutes, test FC, if below 5, repeat until FC holds at 7-10

Probably just not understanding your process.

Take care.

 

[Brentlee98]

I think we're on the same page. I started at 4 gallons (12ppm calculated), but it tested at ~5. Added two more and waited and it tested at 8.5ppm. Added another gallon and still at 8.5ppm. I'll keep testing now every 15 minutes(without adding more) until it maintains 7-10, correct? If it drops below 5, add another 2 gallons. Is this what you would suggest?

 

[Brentlee98]

Currently at 6.2 FC, so I definitely am losing chlorine fast. I'll wait another 15 minutes and if below 5 ppm, I'll add the two gallons.

 

[Brentlee98]

I believe that I did have an ammonia problem, but here's another thought. I have a Delta E-80 UV Water Sanitizer. Should that not be ridding my pool of any bacteria that would turn CYA into ammonia? Anyone have any thoughts on how well these work? No way for me to measure the effectiveness, is there? As far as the problem in this thread, my chlorine consumption has slowed considerably, but I did have to add another 3 gallons. Hopefully, this ammonia is almost gone.

 

[Griswald]

I believe that I did have an ammonia problem, but here's another thought. I have a Delta E-80 UV Water Sanitizer. Should that not be ridding my pool of any bacteria that would turn CYA into ammonia? Anyone have any thoughts on how well these work? No way for me to measure the effectiveness, is there? As far as the problem in this thread, my chlorine consumption has slowed considerably, but I did have to add another 3 gallons. Hopefully, this ammonia is almost gone.

They dont.

 

[mknauss]

You don't keep testing every 15 minutes. It is a one time thing, you take your FC to 10, test in 15 minutes, if FC at 5 or less,, add back to FC 10, wait 15 minutes, if FC between 7-10, STOP. Add CYA to 30 PPM and start SLAM

UV things are not effective in residential settings. They are not big enough to really do anything and the contact time of your water to the devices is too low. Your best idea is to unplug it and save the electricity.

Take care.

 

[Brentlee98]

Thanks, all. Disappointing that I got talked into a UV filter. Pool builder said that it made a clearer pool than salt water, so we opted to go that route. I originally was going salt, but this was supposedly the "newest thing out" and they highly recommended it.

Thanks, Mknause, for the further explaination. I tested CYA yesterday night after getting to 7-10 ppm and it's very low, so I'll add CYA to 30 today and then slam.