My Pool Won't Hold Chlorine!

Causes and cures for cloudy swimming pool water. Milky pool water, white, pink, brown, purple, black cloudy water.

My Pool Won't Hold Chlorine!

Postby Need Pool Help!! » Tue 19 May, 2009 11:22

I opened my pool about a month ago and it will not hold free chlorine. All other levels appear to be fine (I am having my water analyzed by a pool shop). The pool is approximately 23,000 gallons and I have added just over 20 gallons of chlorine over the past 2 weeks. The pool looks clean - it took a few weeks to clean up, but all green is gone. I had the same problem last year, about mid way thru the summer I "lost" all free chlorine and have not been able to get it back. The pool has a sand filter and I replace the sand prior to opening the pool. Any suggestions?
Need Pool Help!!
 

My Pool Won't Hold Chlorine!

Postby chem geek » Wed 20 May, 2009 04:22

I believe I responded to the same question here. Did the CYA level drop between the end of winter and now? If so, then bacteria may have converted the CYA into ammonia and that will take a lot of chlorine to get rid of.
chem geek
Pool Industry Leader
Pool Industry Leader
 
Posts: 2361
Joined: June 2007
Location: San Rafael, California

My Pool Won't Hold Chlorine!

Postby Please help ... at wits end » Wed 24 Jun, 2009 21:03

Is there anyone out there that can figure this mystery out. We have a 20,000 gallon in ground pool and live in central Illinois. This is our 7th year w/the pool. We opened it May 1 and still cannot hold chlorine. We have tried everything (I think). Changed the sand in the filter. 3 phosphate treatments. Currently have no phosphates. Have spent over $1500.00 in chemicals (which should be about 3 season's worth).

Pool was cloudy when we opened it but after the usual routine, it cleared up. However our automatic cover broke and was open for approx. 3 weeks. This was during May when the pollen season was in full force and we also had tons of rain water which we have never allowed in the pool prior to this. We know a few people who struggled to get chlorine to hold this year, but we seem to be the ones who as of June 24th cannot get it to hold. We use Bioguard chemicals and have tried every product they carry, some of them several times. Massive shocks, etc, but within 5 minutes, the chlorine is gone. Our pool people say there must be something eating the chlorine but what could it be? Pool is still clear and we are swimming but very hesitant to continue doing so.

Any ideas or suggestions would be appreciated.
Please help ... at wits end
 

My Pool Won't Hold Chlorine!

Postby Denali » Wed 24 Jun, 2009 21:34

Please help ... at wits end wrote:Is there anyone out there that can figure this mystery out. We have a 20,000 gallon in ground pool and live in central Illinois. This is our 7th year w/the pool. We opened it May 1 and still cannot hold chlorine. We have tried everything (I think). Changed the sand in the filter. 3 phosphate treatments. Currently have no phosphates. Have spent over $1500.00 in chemicals (which should be about 3 season's worth).

Pool was cloudy when we opened it but after the usual routine, it cleared up. However our automatic cover broke and was open for approx. 3 weeks. This was during May when the pollen season was in full force and we also had tons of rain water which we have never allowed in the pool prior to this. We know a few people who struggled to get chlorine to hold this year, but we seem to be the ones who as of June 24th cannot get it to hold. We use Bioguard chemicals and have tried every product they carry, some of them several times. Massive shocks, etc, but within 5 minutes, the chlorine is gone. Our pool people say there must be something eating the chlorine but what could it be? Pool is still clear and we are swimming but very hesitant to continue doing so.

Any ideas or suggestions would be appreciated.


Hi,

First question would be what is your CYA level? Next question is do you have numbers for your chemical balance? FC, TC, pH, TA, hardness?
Denali
Swimming Pool Superstar
Swimming Pool Superstar
 
Posts: 257
Joined: April 2008

My Pool Won't Hold Chlorine!

Postby At Wits End » Wed 24 Jun, 2009 21:51

Here are the vital stats:
Saturation Index: 0.2
TDS: 2200 (down from 3500 after draining half the pool twice)
CYA: 71
Total Chlorine: 1.1
Free Chlorine: 0
PH: 7.6
Total Alkalinity: 148
Adj. Total Alk: 127
Total Hardness: 308

Each time we go the the pool store, they keep telling us we are so close, so we have added bag after bag of shock, but like I said, there's no chlorine after 5-10 minutes. We finally put chlorine pucks in the skimmer baskets, which they think is the result of the 1.1 total chlorine.

Thanks so much.
At Wits End
 

My Pool Won't Hold Chlorine!

Postby Denali » Thu 25 Jun, 2009 16:02

At Wits End wrote:Here are the vital stats:
Saturation Index: 0.2
TDS: 2200 (down from 3500 after draining half the pool twice)
CYA: 71
Total Chlorine: 1.1
Free Chlorine: 0
PH: 7.6
Total Alkalinity: 148
Adj. Total Alk: 127
Total Hardness: 308

Each time we go the the pool store, they keep telling us we are so close, so we have added bag after bag of shock, but like I said, there's no chlorine after 5-10 minutes. We finally put chlorine pucks in the skimmer baskets, which they think is the result of the 1.1 total chlorine.

Thanks so much.


A few thoughts on your pool. With a CYA level of 70 to "shock" your pool you need to hit about 28ppm FC. Sounds like you aren't getting close to that level so the chlorine you do add is used up quickly. I would guess you have the beginnings of algae and then is taking out your chlorine.

The tablets you put in the skimmer will add to your CYA and make the FC level you need to "shock" even higher. Do you know what type of chlorine the bags of "shock" you are using are? If it's dichlor you're adding even more CYA.

To bring the FC level up to 28ppm you will have to add a lot of chlorine all at once (see http://www.poolcalculator.com/ to determine how much you need to add to your pool). Another problem here is you need to be able to measure chlorine levels that high. Most test kits or strips can't do that. There are kits that do and unless your pool store is able to test those levels for you, you might want to invest in one.

There may be something going on in your pool I"m not thinking of that is using up the chlorine that quickly. I would assume algae though and treat accordingly. Throwing in bags of "shock" will often clear a pool but you really need to know what it is adding along with the chlorine and how much is needed to get the job done.

I know I didn't give you a flat out answer to your problem. Don't think I can without being there to see and test the pool. Experience does tell me that with CYA of that level algae is always close by because maintaining the right level of FC generally isn't done. We look at the test kit and read a level of "OK" and think we're fine but it really isn't unless you are basing that FC level on your CYA level.

One last thing, tablets in the skimmer is almost never a good idea. If you run your equipment 24/7 you might be ok but if you turn it off and on and have a heater bad things can happen. The tablets have a low pH.
Denali
Swimming Pool Superstar
Swimming Pool Superstar
 
Posts: 257
Joined: April 2008

My Pool Won't Hold Chlorine!

Postby lectric102002 » Wed 22 Jul, 2009 20:09

Your TDS are way too high. I'd do a water exchange until you get your solids in the 900 range.
lectric102002
 

My Pool Won't Hold Chlorine!

Postby chem geek » Thu 23 Jul, 2009 00:05

It's not the TDS which is mostly just salt. If the pool even had the chlorine level drop to zero, it's possible bacteria converted some of the cyanuric acid into ammonia and that is where the chlorine demand is coming from. The phosphate removers won't do anything to fix that. I suggest you get an inexpensive ammonia test kit from a fish/pet/aquarium store. Your combined chlorine level of 1.1 ppm translates to 0.2 ppm on the ammonia test kit so any level higher than that on the kit is ammonia itself.

It will take roughly 8x the ammonia level to get rid of it, but there could also be some other intermediate chemicals that won't show up on the ammonia test. The key is to add lots of chlorine. I would NOT use any more powder since Dichlor increases Cyanuric Acid (CYA) while Cal-Hypo increases Calcium Hardness (CH). Use 10%/12.5% chlorinating liquid or 6% unscented bleach instead. You should also get your own good test kit -- either the Taylor K-2006 you can get at a good online price here or the TF100 from tftestkits.net here.

You can also read about my own personal experience with the bacteria CYA-->ammonia problem in this thread when I stupidly let the chlorine get to zero when the pool was warming up this spring.

Richard
chem geek
Pool Industry Leader
Pool Industry Leader
 
Posts: 2361
Joined: June 2007
Location: San Rafael, California

My Pool Won't Hold Chlorine!

Postby roydog » Wed 29 Jul, 2009 15:59

I live in Central Indiana with a 9 year old pool and have the same problem--and have had the problem since about the 6th year. Despite spending ungodly amounts of money on every form of chlorine known to man (save gas) trying to achieve the "breakthrough point" the pool seems to have a mind of it's own and has never seemed to achieve breakthrough as a direct result of any of my efforts. It just seems to happen sometime in June. This year was about July 1. One thing that "seems" to help is shocking occasionally with non chlorine shock. My pool dealers written diagnosis always indicates that I have the option of adding about 14 lbs of chlorine shock to achieve breakthrough--or to add 2lbs of non chlorine shock to burn off the chloramines and get the same result---DUUHHHH, wish it was that simple, but it does seem to get me closer.

My main strategy has been, after getting the water clear with no visible algae growth and shocking and chlorinating regularly and otherwise balancing the water--not to worry about it. Nobody's died or gotten ill (knock on wood) so far after 3-4 years of dealing with this.

My CYA disappears totally over the winter so I start each year fresh. I use 3" pucks and dichlor shock until cya gets to about 40. I finish the season using bleach and usually with a cya level of 80-100.
roydog
 

My Pool Won't Hold Chlorine!

Postby mr_clean » Wed 29 Jul, 2009 17:49

if you drain and refill your pool without adding any conditioner only using tabs you will have chlorine loss until you reach 50-60ppm in conditioner level. Then once you start going over this level the conditioner will start making your chlorine weaker causing this same problem.
the best course of action is to have the water tested to know your conditioner level, add what is needed after the winter and use liquide chlorine on a weekly basis. 1-gal of good chlorine is the same as 2-bags of shock but the liquide chlorine does not add anything unwanted like shock. I suggest to stop using tabs for your main chlorine source as you need to use to many to keep chlorine level strong and have to keep testing your water to make sure conditioner level is correct.
User avatar
mr_clean
Swimming Pool Superstar
Swimming Pool Superstar
 
Posts: 398
Joined: August 2007
Location: So Cal

[Show] Post a reply

Next

Return to Cloudy Pool Water


Pool Maintenance   •   Pool Wizard   •   Pool Help   •   Havuz Bakımı