Chemistry out of whack after party

The basics of swimming pool maintenance.
New swimming pool owner's questions.
Help getting started with daily pool care.
sunkissed
Pool Newbie
Pool Newbie
Posts: 9
Joined: Wed 30 May, 2012 19:55
My Pool: Inground, fiberglass over gunite, 65,000 gal, Hayward DE filter
Location: Pennsylvania

Chemistry out of whack after party

Postby sunkissed » Mon 25 Jun, 2012 08:52

Hi - We got our numbers in line for our small community pool - chlorine level held overnight, ammonia - 0 , phos- 0 and opened it for the season. We had a memorial day party with a heavy bather load, many childern, adults staying late into the night. Althought alcohol is not allowed at the pool, an empty case of beer was found.

The next morning the pool was cloudy, would not hold chlorine ( I had it at >8 prior to party). The follwing day I had it tested
fc -.5
pH - 7.8
Alk 165
hardness 275
cya -0
phos - 2500
ammonia -0
any idea what happened???


chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Chemistry out of whack after party

Postby chem geek » Mon 25 Jun, 2012 20:40

With many children and with beer, I suspect a lot of urination in the pool. That creates a rather large chlorine demand. Just add a lot of chlorinating liquid (or bleach) until you get a sustained Free Chlorine (FC) reading. Be sure to use a test kit that doesn't bleach out at high chlorine levels, preferably a FAS-DPD chlorine test as found in the Taylor K-2006 or the TFTestkits TF-100. If you have a cheap OTO chlorine test where you compare the intensity of yellow (high FC shows orange; extremely high red-to-brown), then at least that won't bleach out so can be used as a backup test if you only have a DPD chlorine test where you compare the intensity of pink/red.
sunkissed
Pool Newbie
Pool Newbie
Posts: 9
Joined: Wed 30 May, 2012 19:55
My Pool: Inground, fiberglass over gunite, 65,000 gal, Hayward DE filter
Location: Pennsylvania

Chemistry out of whack after party

Postby sunkissed » Wed 27 Jun, 2012 12:49

Thank-you for the reply. We use a DPD test kit. When chlorine is high I use half distilled water and half pool water, test as usual, multiply result by 2... then compared it to 100% pool water and got 'way more than 5'. so I dont think the chlorine test we use bleaches out at too high a chlorine level.

After the party I wanted to super shock it with liquid chlorine, and from reading your forum, thought you would suggest it. but was chicken. I was slow on the draw to ask etc and went with the traditional suggestion from pool store. I used a phos elim. Very expensive - the water turned very cloudy, phos binder worked creating lots of stuff to vacuum up daily for 5 days, the DE filter had to be backwashed about every 6 hours and taken apart and the panels cleaned 2x. Our phos is down to 100, it cost $600 in chem and labor, plus my free labor and headache.

Was it worth it?If I didnt do it would we have been prone to algae outbreak? especially during a party weekend... and I hate to ask this - what are the effects of urination in the pool? and suggestions on preventing????
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Chemistry out of whack after party

Postby chem geek » Wed 27 Jun, 2012 21:30

You just bought very expensive insurance. It wasn't necessary since chlorine alone will prevent algae growth regardless of nutrient level (because algae growth is ultimately limited by sunlight and temperature). Worst case, you would have just shocked the pool with chlorine to get ahead of whatever was consuming it (be it ammonia/urea from the kids urinating or from nascent algae growth). The cloudiness is from the lanthanum phosphate precipitate since that's how phosphate removers work though the better ones usually have a clarifier in them to clear the water faster. Anyway, you didn't cause any harm, except to your wallet, and now your pool will be less likely to get algae if the chlorine level gets too low relative to the CYA level. Like I said, you just bought expensive insurance, that's all.
sunkissed
Pool Newbie
Pool Newbie
Posts: 9
Joined: Wed 30 May, 2012 19:55
My Pool: Inground, fiberglass over gunite, 65,000 gal, Hayward DE filter
Location: Pennsylvania

Chemistry out of whack after party

Postby sunkissed » Thu 28 Jun, 2012 07:46

Thank-you very much for your reply! That is how I will handle the situation if (when?) it happens in the future.

If I would have kept the FC @ 10 through 3x daily test/ treat with liquid chlorine during the 2 party days would i not have had the phos prob? or is the only solution to change the party goers?

Anyone have any suggestions on how to stop people from peeing in the pool??? When it is a small community pool??
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Chemistry out of whack after party

Postby chem geek » Fri 29 Jun, 2012 01:11

Forget the phosphates part of the issue since it is irrelevant. The issue is one of chlorine demand and what you are dealing with is something that commercial/public pools deal with all the time. They ask for people to shower, but they don't. They ask them not to treat the pool like a urinal, but they don't. So they just have sensors (or manual testing) and feeder systems (or manual dosing) done frequently enough to stay ahead of whatever chlorine demand is thrown their way.

Also, I just noticed that you initially wrote that you had 0 ppm CYA, is that correct? If this is an outdoor pool, then your loss of chlorine was likely also due to the UV in sunlight. You can't have a manually dosed chlorine pool outdoors exposed to the sun and not have any CYA in the water -- the chlorine will get broken down way too quickly by the sun. It will also be too strong and harsh (unless you keep the FC very low, which is impractical). Is there any particular reason the CYA is zero? Was that intentional? Even if this is an indoor pool, a small amount of CYA (say, 20 ppm) helps to moderate chlorine's strength allowing you to have a higher FC so you can have a greater buffer (margin) of chlorine. I don't think you'd need to go to 10 ppm even with a lot of people in the pool.
sunkissed
Pool Newbie
Pool Newbie
Posts: 9
Joined: Wed 30 May, 2012 19:55
My Pool: Inground, fiberglass over gunite, 65,000 gal, Hayward DE filter
Location: Pennsylvania

Chemistry out of whack after party

Postby sunkissed » Fri 29 Jun, 2012 08:14

Thjank-you for the reply! I will ignor the phos in future. cya was 25 prior to and after the reading in my post. it was 65 at last analysis. I have been letting the pool store do it, maybe i should pick up the test chems and do it myself. I didnt know if any of the wild swings in chemisty would be responsible for a false readings.

We have an off line chlorinator and use 3 inch tabs. Use liquid chlorine for shock.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Chemistry out of whack after party

Postby chem geek » Fri 29 Jun, 2012 23:59

Pool store results are often notoriously inaccurate, especially for the CYA test. Get your own test kit -- either the Taylor K-2006 or the TFTestkits TF-100 .

Return to “Basics for New Pool Owners”

Who is online at the Pool Help Forum

Users browsing this forum: No registered users and 0 guests