no chlorine

Chlorinating, maintaining the right chlorine levels,
chlorine problems. Dichlor, trichlor, cal hypo, bleach,
granules, chlorine pucks and chlorine sticks.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2381
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Postby chem geek » Thu 11 Sep, 2008 02:00

OK, now this makes much more sense. There really isn't "chlorine lock", but it does seem like it. What is happening is that the CYA level is high enough to make the chlorine less effective because the FC level wasn't raised to keep the FC/CYA ratio constant. So algae grows faster than chlorine can kill it which makes the water cloudy (it would eventually turn into a full-fledged algae bloom), the chlorine gets used up and forms Combined Chlorine (CC) and the high CYA level makes the oxidation of this CC very slow.

Adding lots of chlorine raises the FC high enough to accelerate the oxidation of the CC and the killing of algae faster than it can grow.

So that's perfectly explained. However, if the CYA level isn't lowered somehow, the situation can repeat itself unless the FC level is kept higher. So perhaps the high chlorine level also lowers the CYA level somewhat as well.

That's my best guess of the situation though it would not explain the before/after nitrate measurements.

Richard


pool person

Postby pool person » Thu 11 Sep, 2008 15:18

alright i see.. I work at a pool store in Mt. Holly, New Jersey. Do you think you can explain the whole CYA/ FC ratio? I have worked there for quite some time now and me nor my boss know about the deal with high CYA and the ineffectiveness of chlorine. if you could either explain it or give me a link to a good site about it that would be great. and/or give me different pool situations with a problem with CYA And chlorine. Thanks
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2381
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Postby chem geek » Thu 11 Sep, 2008 17:24

Basically, the active form of chlorine is hypochlorous acid that does most of the disinfection killing bacteria, inactivating viruses, killing algae and oxidizes organics. Hypochlorite ion is far weaker by orders of magnitude, but most (about 97%) of what is measured as Free Chlorine (FC) is actually in the form of chlorine combined with Cyanuric Acid (CYA) in a series of compounds called chlorinated isocyanurates that are almost inert. They do not disinfect nor oxidize to any great extent. They do, however, release the chlorine as hypochlorous acid as this gets used up.

This post shows the traditional industry graph of hypochlorous acid concentration as a function of pH when there is no CYA and then shows the true graph when CYA is present. The NSPF CPO and APSP TECH courses don't teach this for whatever reason.

The amount of active chlorine, hypochlorous acid, is proportional to the FC/CYA ratio. So if you double the amount of CYA in the water, then you need to double the amount of FC to have the same level of disinfection, oxidation and algae prevention. It's easy to have CYA rise when using stabilized chlorine since the following are chemical facts independent of concentration.

For every 10 ppm FC added by Trichlor, it also increases CYA by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by 7 ppm.

The technical derivation for the FC/CYA ratio is described here and some qualitative descriptions are also found here in extracts from the original paper presented at a 1973 symposium and published in 1974.

The stabilized chlorine industry has been touting the mantra "CYA doesn't matter; only FC matters" for whatever reason and unfortunately this has also led to the belief that "CYA should not be used in indoor pools; it only protects chlorine from breakdown from sunlight" which is only a half-truth since it leaves out the significant fact that it reduces the active chlorine concentration. This means that pools without CYA, such as indoor pools, are over-chlorinated by orders of magnitude with 10-30 times the amount of hypochlorous acid concentration needed. This leads to much faster degradation of swimsuits (elasticity gets shot), flaky skin and frizzy hair as my wife experiences during the winter at a community center indoor pool while in our own pool during the summer there are none of these problems even after 5 years.

Richard
MunchaBunch

High content of Phosphate and Nitrogen

Postby MunchaBunch » Sun 03 May, 2009 13:07

I went to the pool store and they claim I have a high content of Nitrogen (70 ppm) and Phosphate (2,500 ppm) in my swimming pool. It is very likely that fertilizer from my yard got in the pool. The store recommends that I drain the pool and filter. This would be an expensive venture as water rates have recently gone through the roof.
Will the nitrogen and phosphate levels reduce as time goes by or is this an ongoing ordeal that sooner or later I will have to drain the pool? Is this hazardous to swim in? :problem:
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2381
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

no chlorine

Postby chem geek » Sun 03 May, 2009 18:07

Until recently, I had 2000-3000 ppb of phosphates in my pool (not sure what my nitrates level was) and have kept the pool free from algae growth through maintaining the proper FC/CYA ratio. I diluted my pool water with winter rains and didn't retest the phosphate level (I don't really care about it).

The nitrates and phosphates will lower over time with water dilution (NOT evaporation and refill, however, but by splash-out, backwashing, rain overflow, etc.). Evaporation and refill can actually increase phosphate levels as happens in my pool because 300-500 ppb phosphates are in the fill water (they are used for corrosion control by the water district). It is not hazardous to swim in.

You should read the articles in the Pool School and look at the Chlorine / CYA Chart to see what FC level you need for your CYA level to prevent algae growth. You can use 50 ppm Borates in the pool to help inhibit algae or you can use a weekly PolyQuat 60 algaecide or a phosphate remover, all at extra cost (the phosphate remover will be initially very expensive since the phosphate level is so high). If you use these supplements, then you can maintain a somewhat lower FC level. Otherwise, you need to follow the chart.

The biggest problem with a pool high in phosphates and nitrates is that it is rather unforgiving if you ever let the FC/CYA ratio get too low. Algae can grow quickly in such a pool so you need to watch your chlorine levels very carefully or use one of the supplemental products I mentioned. Also, realize that if you are using stabilized chlorine (Trichlor or Dichlor) then you are increasing your Cyanuric Acid (CYA) levels which makes the chlorine less effective. If the CYA is doubled at the same FC level, then the chlorine is half as effective and could kill algae slower than algae can reproduce at which point you get unusual chlorine demand, dull water and eventually cloudy and then green water from an algae bloom.

Richard
newpool1
I'm new here
I'm new here
Posts: 3
Joined: Mon 04 May, 2009 14:44
My Pool: above ground roughly five and a half feet in height and a diameter of 21 ft obviously round. 10000 gallons. Sand filter.
Location: england

No chlorine

Postby newpool1 » Mon 04 May, 2009 16:05

Hi
I am new to this site and the pool business, and was after some help on a couple of things if possible.
My testing strips have four tabs Chlorinity, Alkalinity, Stabliser and ph these work great the problem being with the results. Two are in spec but the other two being Chlorinity which is reading slightly higher than zero and Alkalinity which is the opposite being too high at 240.
Ph and Stabaliser are fine.
I have shocked the pool by the way.
ANy suggestions ???
Thanks Rich
Me...
Swimming Pool Superstar
Swimming Pool Superstar
Posts: 302
Joined: Thu 26 Feb, 2009 11:11

No chlorine

Postby Me... » Mon 04 May, 2009 16:48

Strips are ok for quick tests but if you really want accuracy get a drop test kit like a Taylor 2005 or such. Expensive on its own, but a small price to pay for the help it will give you.

You are going to have to get the Alkalinity down by adding acid. Post your pool type and gallonage and I am sure Chem Geek will pop in and tell you exactly how much to add. In fact do a search (he seems to know the URLS to all the info) and you find 50 posts telling people how to do it. His ideas differ from mine a but until he chimes in go dump a cup of acid in the pool in one spot. Wait a few hours and repeat as needed. I have no idea how big you pool is so I have no idea how much you need.

Get the chlorine up to maybe 2-3ppm for now

You don't even mention calcium hardness and its important. Get a test for it.

Post your reading please and not just that they are in range.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2381
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

no chlorine

Postby chem geek » Mon 04 May, 2009 20:15

If you are going to get a new test kit, spend more and get the Taylor K-2006 at a good online price here or the TF100 kit here with the latter kit having 36% more volume of reagents so less expensive "per test". These tests have a FAS-DPD drop-based chlorine test that will measure to within 0.2 ppm and up to 50 ppm. You can see a demo of the chlorine test here.

Though you can lower your TA by following the procedure in this post, since your pH isn't high and you don't know your other water chemistry parameters and haven't described any problems, I'd wait to get a full set of water chemistry parameters before proceeding further. If you want to lower your TA at least some, that's OK, but we won't know how far to go until we see what else is going on. By the way, what kind of chlorine are you using? Trichlor pucks/tabs? Cal-Hypo granular? Chlorinating liquid or bleach? Something else? You say you shocked the pool -- why? Do you have algae? If you have the latter, then read Defeating Algae, though it will be hard to know what Free Chlorine (FC) level you need to get to since we don't know your Cyanuric Acid (CYA) level.

Richard
User avatar
XtremelyTropical
Pool Enthusiast
Pool Enthusiast
Posts: 24
Joined: Fri 27 Feb, 2009 09:53

No chlorine

Postby XtremelyTropical » Tue 05 May, 2009 21:15

Have you tried using liquic chlorine?
Artificial Palm Trees and NEW Palm Tree Mailbox! http://www.xtremelytropical.com - Commercial grade/Residential Pricing. Seeking Distributors.
Spudwrench

No chlorine

Postby Spudwrench » Mon 11 May, 2009 07:10

You have what is called a chlorine lock. If I recall correctly, you have to drop the Ph level to release it. You can chlorinate ALL you want and it won't register on your test kit. Depending on the volume of water, drop the Ph below 7.0 ppm and I THINK you will be all set, then adjust it back.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2381
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

no chlorine

Postby chem geek » Mon 11 May, 2009 21:10

There is no such thing as "chlorine lock" and lowering pH won't help. There is sometimes an insatiable chlorine demand. If one has algae, then that takes chlorine to kill it. If one lets their pool go, say over the winter, and it had Cyanuric Acid (CYA) in it, then soil bacteria can grow and convert some or all of the CYA to ammonia (and intermediate products) as described technically here.

The only way to get rid of the ammonia and byproducts, if they are present, is to oxidize them and that may take a lot of oxidizer (such as chlorine). One can do a bucket test to see how much chlorine it takes before it starts to register. 1/8th of a teaspoon of 6% bleach in 1 gallon is 10 ppm.

If, on the other hand, one has an algae bloom, then if the CYA level is very high, it's better to do a partial drain/refill to lower the CYA level than to have to add a lot of chlorine to raise the FC high enough to kill the algae quickly.

Richard
kd

Algae problem

Postby kd » Sat 16 May, 2009 09:24

Ok, I have a algae problem, my chloride level is good according to the test kit. I had the water tested and was told I have zero phosphates.
I just put in 5lbs of alkalinity rise becuase that was a bit low...... My pool is deep green.... The filter is on 24/7 the aquabot is in there 24/7....
I'm at a loss.
Please help....
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2381
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

no chlorine

Postby chem geek » Sat 16 May, 2009 13:02

You said "chloride" level, but I believe you meant "chlorine" level. If your pool is a CLEAR deep green, not cloudy murky dark green that looks like algae, then you could have a lot of copper in the water. Did you have the water tested for metals?

Otherwise, if it's algae, then it is unlikely for you to have any Free Chlorine (FC) though could have Combined Chlorine (CC). You really should get your own good test kit, either the Taylor K-2006 you can get at a good online price here or the TF100 kit from tftestkits.net here with the latter kit having 36% more volume of reagents so is less expensive per test.

If you do have algae, then read Defeating Algae.

Richard
Bob PA

No chlorine

Postby Bob PA » Wed 20 May, 2009 07:31

new owner wrote:I have had problems with my pool not registering any chlorine, I have had my water tested (leslie's pool supply) every 3 days for 3 weeks, they tell me everything else looks fine but no chlorine, I have shocked my pool 4xs over the past 3 weeks put over 16lbs of shock, and still no chlorine registering. I have a chlorinator and the tabs are disolving about every 5 days. Please give some help its driving me crazy and dont know what to do!!!!

Thanks

New Pool Owner


I have an in-ground pool and have had the same problem. I have been a pool owner for 18 years. The chlorine lock was broken a couple of times by adding liquid chlorine (two 5 gallon containers).
One time it did need stabilizer.
Your pool company that you go for the water testing should be advising you on what to do.

I hope this helps.
bullyrider
I'm new here
I'm new here
Posts: 3
Joined: Tue 02 Jun, 2009 11:48
My Pool: 16 x 32 inground. concrete deck, sand filter.
Location: Newnan, Ga

No chlorine

Postby bullyrider » Wed 03 Jun, 2009 06:01

This is "chlorine block", super shock you pool with about 7-8 pounds of shock and you should be good to go. :thumbup: I had this problem last year when I opened mine.

Return to “Chlorine”

Who is online at the Pool Help Forum

Users browsing this forum: CommonCrawl [Bot] and 0 guests