Chlorine Block?

I have opened my pool recently, a 20 X 40 inground pool. The pool was initially shocked upon opening and water tested for all chemicals. All chemicals have been adjusted accordingly, with the exception of the chlorine. Initial testing showed very litte chlorine; therefore, pool was shocked again. After shocking, the chlorine level went to zero; therefore, the pool store had me shock again. This still resulted in a chlorine level of zero. After shocking 3 times, the pool store advised that I had a chlorine block and the best way to solve this problem was to drain 1/3 of the water and start over; otherwise, I would need to add over 2,000 lbs of shock. Thus, this is where I am at. I've always understood shock to increase the chrlorine and don't understand a chlorine block, if that is what I have? Can anyone help? Thanks!

Before you add anything else to your pool, I would post a complete set of numbers here: FC, TC, CYA, TA.....Then you can get some answers on what the problem is :)

MaryLee is right..post a set of test results from a drop-based kit for TC, CC, pH, CYA, and T/A. And if your pool isn't vinyl, then also for Ca, along with what ingredient you're using to shock. That will help us get you steered in the right direction.

Janet

Ouch. Sandyfreckles, you have been "Pool Stored". They sell you stuff and sell you stuff and you spend money and when the garbage they sell you doesn't work, they tell you it's YOUR fault and make you drain and refill. What a scam!

Luckily, you've come to the right place. Most of us are pool owners, not dealers, and have been sharing effective information for years.

Step one: Have them retest the water and GIVE YOU THE TEST RESULTS! They should have a printout, if not, write them down. We need the following test numbers, and most are in ppm--Parts Per Million.
a) FC--Free Chlorine--the good stuff that cleans your pool
b) CC -- Combined Chlorine or, more properly, Combined Chloramines--the used up chlorine that smells like a pool and irritates eyes. The goal is for this to be 0 ppm.
c) pH -- Same as high school chemistry--how acid or alkaline your water is. 1 is acid, 14 is alkaline, 7 is technically neutral but pools are effectively neutral when they are in the 7.3 to 7.8 range.
d) Total Alkalinity or T/A -- Despite its name, it's a measure of how resistant to changes in pH your pool water is. Too low means your pH will ping-pong, too high means scaling. 80ppm to 125ppm is the normal range
e) Calcium or Calcium Hardness or Total Hardness -- all the same thing. Since you said you have an inground, I'm guessing it's concrete or plaster or tile. Ca should be 200ppm to 400ppm for this. If it's vinyl lined, Ca can be ANYWHERE from 0ppm to 500ppm with no problem--Calcium in the water protects the walls from leeching calcium from the plaster or concrete--vinyl isn't affected by it.
f) CYA or Stabilizer, Conditioner, or Cyanuric Acid. --This is very important and is probably what the idiots at the pool store mean by "Chlorine Lock". There is no such thing as "Chlorine Lock". What it means is that your CYA level is so high they don't know what to do. We do. CYA is needed to prevent rapid breakdown of chlorine in sunlight (UV is hard on it). But too much slows it down so it doesn't work. The solution is more chlorine. We normally recommend levels of 30ppm to 50ppm but we can deal easily with levels up to 100ppm (what the ignoramouses at the pool store call "chlorine lock") and even beyond. The cause of it? You won't believe it! The powdered "shock" they keep selling you! It's stablized chlorine, either Di-Chlor or Tri-Chlor and it adds LOTS of CYA as it adds chlorine. Using it only makes your problem worse.

g) they'll give you lots of other numbers, like TDS (total dissolved solids), Acid Demand, Base Demand. We don't need them. If they give you a copper or iron test value, we should see that. They'll also push phosphate tests because phosphate remover is very expensive and they make lots of money on it. Don't be suckered into buying phosphate remover--it's the LAST ditch effort--we have lots of things that work that you do first. And you can always go back and buy it if you REALLY need it (one out of 1000 do, the rest are told they do).

Now, you should ONLY use bleach to chlorinate. Lots and lots of bleach. How much, I won't know till we see those test numbers--plus we need to know the volume of your pool, preferably in gallons, but cubic feet is fine.

You will also need to get your own high-quality test kit that measures this stuff. PoolSolutions.com has the best a home-owner can buy, but Leslies's on-line sells a complete kit with FAS-DPD chlorine testing that's very good. (Don't confuse DPD and FAS-DPD testing--they are not the same). We don't recommend test strips because they aren't precise and are MUCH harder to get an accurate reading from than most people realize. They are OK in an emergency, and are better than nothing, but not much.

Gotta go--my turn to take care of the baby!:rolleyes:

I went throught the exact same scenario 2 years ago. I opened with new water, shocked, couldn't get chlorine to register on my testing sticks. Neither could the pool store. They told me to keep shocking daily and eventually an FC would show up. I went through a 50# of dichlor in 2 weeks. I called BS. They called the manufacturer, blamed it on a "bad batch", gave me a replacement 50#s. They also through out the "chlorine block", so I did another drain and refill (with a vinyl liner, something else the advised me to do :( ). Started over.

Only added half the shock this time, got a very high FC reading on my sticks. Took a sample to the pool store, they did as well. Turned out they were using sticks to test as well, and I'll bet a donut the first sample bleached out the test strip from high chlorine.

Basically they made me nuke my liner and sold me way too many chemicals.

Thank God for this place.

First of all, thanks to everyone who has responded. To answer your questions, my pool holds 35,000 gallons of water. I am using a brand of chemicals called Bioguard, which is purchased at the pool store. Prior to draining my pool of 1/3 of the water, the readings were as follows: CYA: not tested; Total Chlorine 0; free chlorine 0; PH 7.7; alkalinity 158; calcium hardness 129; iron and copper - not tested.

After draining the pool 1/3 and refilling; I then added another 6 lbs of shock and moved the chlorinator dial from 2 1/2 setting on the dial to a 3 setting.

Water was tested today, results are: CYA - not tested; Total chlorine - 0; free chlorine - 0; ph - 7.2; alkanlinity - 95; calcium hardness 100; they have advised to add chemicals (since i drained water) to raise alkanlinity; add chemicals to raise ph; add chemicals to raise calcium, SHOCK AGAIN and they advised me to move the chlorinator dial up to 4. I'll retest in 24 hours at the pool store.

I used a home testing kit (not the strips) yesterday and had chlorine readings; but the pool store had no chlorine readings. they said the test kit chemicals i was used was probably expired and i was getting false readings. i looked at the chemicals and they had expired.

Hope this will help you resolve my problem. thanks again

"Chlorine lock" is a pool industry term, with no specific meaning, which functions as an all-purpose official stand-in for "We don't know what's going on with your pool".

It's sort of like when you go to the doctor, and say, "Doctor, my skin is irritated" and he says, "Yes, ma'am, you are suffering from dermatitis, and here's some cortisone." Dermatitis just means irritated skin . . . but you already knew that; chlorine lock just means your chlorine isn't doing what the store expects . . . and you already knew that, too!.

Of course, it is possible that you've got some chlorine that's 'weak'. However, in 20+ years in the industry, I've never had that happen to me.

I'm guessing you may have a huge chlorine *demand*, which just means that there's something -- I don't know what -- that's consuming, or reacting with, the chlorine in your pool. One common possiblity, with newly opened pools, is that you had lots of stabilizer last year, and now have none due to biodegradation. When bacteria 'eat' your stabilizer, they 'poop' out ammonia and urea. Sometimes -- but not always -- other bacteria then 'eat' the ammonia and urea, and poop out nitrogen gas. If the biodegradation goes all the way to nitrogen gas, you lose the stabilizer, but have no residue. But, if the process stops with the ammonia and urea, you STILL lose the stabilizer, but end up with the ammonia and urea in the pool.

And guess what? It takes HUGE amounts of chlorine to destroy the ammonia and urea.

One other indicator is the fact that your test results showed chlorine. By any chance, were you using a test (OTO drops??) that shows *total* chlorine? If so, you would have showed the 'combined' chlorine that forms when chlorine is trying to destroy the nitrogen compounds, but the free chlorine test used by the dealer would have showed nothing.

Here's what I recommend:

• If you have an OTO chlorine test, use it, and post the results. OTO does NOT go bad! If you don't have such a test, spend $5 and get one from Walmart, Kmart, etc.
• Get your dealer to test your stabilizer and tell you what the results are. If you had a bunch last fall, and none know, that's a pretty good clue.
• Get 10 gallons of bleach, and dump them into the pool in the EVENING. Be sure the pump is running. Wait an hour, and then test with OTO. If you get a reading with OTO that gets darker with time (over a 10 minute period) that's another indicator.

Assuming the problem is what I suspect, the solution will be repeated doses of bleach. The 2,000 lbs of shock your dealer suggested is ridiculous. If you want to know how much bleach it will take, you can test and see.

• Take a glass or stainless mixing bowl fill it with one gallon of pool water.
• Add 1/2 teaspoon of 6% household bleach. Stir with a plastic or stainless utensil and allow it to sit for 4 hours. Be sure that it is NOT exposed to sunlight. Then use your OTO test to test the water in the bowl; if you the results show 3 ppm of chlorine instantly, you are good to go. If not, repeat doses and 4 hour waits till you DO have 3 ppm.
• Each 1/2 teaspoon dose amounts to approximately 40 ppm of chlorine; on your pool that would be 20 gallons of 6% bleach*

If you don't want to test, but have good indication that it is just stabilizer 'residue', repeated 10 gallon doses should clear it up in a week or so, at a fraction of the cost of the dealer's chemicals. But, be SURE to add the bleach late in the evening. Otherwise, you'll lose it to sunlight before it can react with any urea.

Of course, if you have a concrete pool that can be safely drained, and cheap fill water, it might be easier to drain and refill. But, probably not.

Best wishes.

Ben "PoolDoc"

* I think I got the math right, but feel free to check. I used the following factors:

• 768 tsp / gallon
• 8.345 lbs / gallon water
• 9 lbs / gallon 6% bleach (this may be high)
• 0.54 lbs Cl2 equiv per gallon 6% bleach
• 30,000 gallon pool (estimate -- high if no deep end)

OK...a little tough love here...this pool store is NOT helping you....so stop going there.

why aren't they testing your CYA? I assume you have none...and that is the first place to start....you need a decent amount of CYA in order to more effiently use your chlorine.

What are you using for shock? And what are you using for chlorine? If it were mem I would add 4 gallons of store nought 6% clorox and then take a reading yourself...then add 2 gallons everytime the FC level drops below 5ppm....just to see if you can sustain FC in the pool. You also should think about raising your PH....but right now you need to get and keep FC in the pool.

To add to what Pooldoc has said, your T/A is fine, leave it alone. And if your chlorinator is using 3" pucks, stop using those and your pH will start to rise--they are very acidic and will continue to drag your ph down as long as you use them.

Janet