Chlorine not registering

shhurs · Postby **shhurs** » Sun 19 Sep, 2010 14:59

I did watch the video last week and that is how I am testing.

James Watson · Postby **James Watson** » Sun 19 Sep, 2010 17:38

The reason you need to keep shocking is that there is something in the water that is eating up your chlorine. It is probably algae. It is important to fully oxidize all of the algae or it will continue to grow and get much worse.

You will know when the shocking process is complete when your overnight FC loss is less than 1.5 ppm and your CC is less than 0.5 ppm.

You should measure your FC and add enough bleach to get it to 25 ppm. Remeasure after 1 hour to see what the level is. When you measure after 1 hour, you should get close to 25 ppm. Measure again in the morning to see what your overnight loss is. If your overnight loss is more than 1.0 ppm, or your CC level is higher than 0.5, you need to continue to shock to 25 ppm.

Use this procedure to test.

1. Rinse and fill large comparator tube to the 10 ml mark with water to be tested.

2. Add 2 dippers R-0870. Swirl until dissolved. If free chlorine is present, sample will turn pink.

3. Add R-0871 dropwise, swirling and counting after each drop, until color changes from pink to colorless.

4. Multiply drops in Step 3 by drop equivalence 0.5 and record as parts per million (ppm) free chlorine (FC).

5. Add 5 drops R-0003. Swirl to mix. If combined chlorine is present, sample will turn pink.

6. Add R-0871 dropwise, swirling and counting after each drop, until color changes from pink to colorless.

7. Multiply drops in Step 6 by 0.5 and record as ppm combined chlorine (CC).

OTO is usually pretty reliable for giving you a rough estimate of the total chlorine level, so I'm not sure why there seems to be some discrepancy with the FAS-DPD test.

shhurs · Postby **shhurs** » Sun 19 Sep, 2010 19:12

added 240 oz bleach at 4:30 pm; tested for chlorine only (no other tests) at 6 pm.

FC 8.6 ppm
CC 1.0 ppm

I'll see hor it is in the morning. Seems to disappear overnight.

James Watson · Postby **James Watson** » Sun 19 Sep, 2010 19:22

OK, 240 ounces should raise your FC by 8.6 ppm, so that seems to correspond to what you are seeing.

You should add 459 more ounces of bleach to get to 25 ppm.

It looks like you're still using the 25 ml sample size. You will save a lot of reagent by switching to the 10 ml size.

duraleigh · Postby **duraleigh** » Sun 19 Sep, 2010 19:26

I may be repeating earlier information in this thread but it is important to understand that chlorine is consumable. The instant you put it in your pool, it starts to diminish.

How fast it diminishes depends on how much organics (including algae) is in your pool and how much CYA you have to protect it from the sun.

Sun and organics are the two reason chlorine diminishes. The rate at which yours is being consumed indicates you still have organics.

The solution to that is to continue to add high levels of chlorine until the organics are all killed. The chlorine will then be reduced by somewhere around 2-4ppm daily because of the loss from the sun.

Chlorine is never completely constant in your pool.....you will always have some loss.

shhurs · Postby **shhurs** » Mon 20 Sep, 2010 05:58

Better results this morning. After adding the bleach last night and have FC of 8.6 and CC of 1.0 I tested just now and FC is 4.5 and CC 1.0. So off to work soon but will check later tonight and add more bleach as per the pool calculator. The OTO test this morning showed 4.5-5 so more consistent result - Yeah.

duraleigh · Postby **duraleigh** » Mon 20 Sep, 2010 07:52

I suggest you not bother with the OTO test until you have cleared the pool. (passed the overnight FC loss test)

The OTO test is never very accurate and serves little purpose if are already doing the FAS/DPD test

shhurs · Postby **shhurs** » Mon 20 Sep, 2010 08:15

good. So now, when I test later this evening determine chlorine loss and add bleach to bring up to 10.0 ppm, right?
I'm hopeful that I'm nearing the end of this, whew!

I had bought the OTO test while waiting for my Taylor kit arrive.

James Watson · Postby **James Watson** » Mon 20 Sep, 2010 09:58

Definitely better results. You are starting to hold some FC overnight. You still lost 4 ppm, which is more than the 1.0 maximum loss we are going for. The CC level is not super high, but still needs to come down to less than 0.5.

I recommend that you raise the FC to 20 ppm tonight. I know that it seems high, but with a cyanuric acid of 100 ppm, it is actually equivalent to less than 1 ppm and no cyanuric acid. chem geek can tell you the exact amount, but it really is low. This is one of the hardest concepts for people to get about the FC/Cya relationship.

Since the 100 ppm cyanuric acid slows the chlorine's reaction down so much, it makes it hard for the chlorine to clear the organics at less than 20 ppm.

shhurs · Postby **shhurs** » Tue 21 Sep, 2010 05:49

I added the 459 oz of bleach last night to achieve 20 ppm. This morning's readings:
FC 7.5
CC .5

James Watson · Postby **James Watson** » Tue 21 Sep, 2010 11:53

I think that most of your CC is gone. There is still too much overnight FC loss, which indicates that there are still organics that need to be oxidized.

Add 490 ounces of bleach today. After the sun goes down, measure the FC and CC and then measure them again in the morning. You will know when you can stop shocking when your overnight FC loss is only 1.0 ppm.