I can't get ANy test method to register chlorine

[Herbie]

No matter how much chlorine I add to my tub, I cannot get any test method to read any chlorine levels at all.  What's up?  I have a 360 gallon tub, and I add 1/4 to 1/2 oz. of dichlor every time I use the tub (approx. twice/week, 2 adults, 30 minutes).  I shock it with MPS about every 3 weeks.  All other levels (pH, hardness, alkilinity) are in balance.

I've had my tub for almost a year, and had been using test strips to calibrate my water.  I got a Taylor test kit this summer, which surprisingly showed my test strips to be 100% accurate.  Just this morning I threw in 1/2 oz. of chlorine, waited 10 minutes, then used the Taylor kit.  It showed no chlorine at all - nothing free or combined, zip zero zilch.  What am I doing wrong?

BTW, I have not had any problems with keeping the water healthy (or so it seems).  The water is pretty much odor free, no ickyness to it, and totally clear.

[96SC]

Sometimes if you have too much chlorine it will bleach out a test strip making it look like there is nothing where it really is waaaaaaay too much.  With a strip, at least the type I'm familiar with, if you put the strip into the water and it turns black for an instant then turns white again the color (black) is quickly bleached out.  I'm not sure how a Taylor kit would react to a very high chlorine amount.

Good Luck

[Chas]

What was just posted is true, however, I doubt a half ounce would do it.

Toss in another half ounce and see if you get a reading.

 8-)

[Brewman]

You could also take a water sample to your dealer and see what they find out.  
Is it possible for the reagents in a liquid kit to go bad?  

[tinybubbles]

Have you bought new dichlor lately?  Could you have gotten the wrong thing or grabbed the wrong bottle?  You could try putting a drop or two of household bleach in a cup of water and testing that with your kit.  1/2 ounce is equal to 3 teaspoons, is that right?  That should definately register in a spa your size.  Any chance bromine has been introduced to the water?  That could be converting the chlorine to bromine when added to the tub and therefore wouldn't show up when tested.  How long has it been since your last refill on the tub?  Is it possible that there is something lurking in the spa that is using up the chlorine this fast?  Only dosing with chlorine 2 times a week seems skimpy to adequately sanitize.  Do you do anything in addition to the dichlor and mps?  Mineral sanitizer, ozonator?

[Herbie]

Great questions!  Here's what I can tell you.

The Taylor kit is brand new.  It also confirms the test strip readings.
The dichlor is 12 months old.  It is Leisure Time Spa 56.  The tub has never been near bromine.  It has a mineral/silver cartridge and an ozonator.  It has been 4 months since a refill, but this occurred even when the water was brand new.  I'm as stumped as anyone.

[tony]

Great questions!  Here's what I can tell you.

The Taylor kit is brand new.  It also confirms the test strip readings.
The dichlor is 12 months old.  It is Leisure Time Spa 56.  The tub has never been near bromine.  It has a mineral/silver cartridge and an ozonator.  It has been 4 months since a refill, but this occurred even when the water was brand new.  I'm as stumped as anyone.

Take a small container full of your spa water and add a little bleach to it...then test for free chlorine.  If you get a reading you need to add more chlorine to your spa.

[Vinny]

It sounds like you have a chlorine demand. Since you have used 2 different methods and the chlorine isn't registering - add 3 tablespoons of dichlor and see what happens. This should give you some reading.

Before doing that, get a glass of water and add a couple of grains of chlorine (10 maybe) and see if anything registers. If it does then the taylor/strips are working and you know the dichlor is good.

If you do have a chlorine demand maybe do a chemical cleansing in case a biofilm has grown.

Just an FYI, I have a 400 gallon tub and I just started using the spa frog with 24/7 ozone and I added 1 teaspoon of chlorine and I had a slight residue the next morning.

[Herbie]

I just dumped one ounce of dichlor in, waited 15 minutes, and checked with both methods.  The test strip showed nothing, but the Taylor showed around 5 ppm FC and 15 ppm TC.  Does that sound appropriate?  At this point, should I just leave it be, or should I shock it with MPS?

BTW, it looks like the test strips, while accurate for the other readings, is useless for chlorine.

[tony]

I just dumped one ounce of dichlor in, waited 15 minutes, and checked with both methods.  The test strip showed nothing, but the Taylor showed around 5 ppm FC and 15 ppm TC.  Does that sound appropriate?  At this point, should I just leave it be, or should I shock it with MPS?

BTW, it looks like the test strips, while accurate for the other readings, is useless for chlorine.

It does not sound right.  Your readings are indicating a 10 ppm combined chlorine level which is extremely high.  I think it is more likely that your chlorine levels are so high that you're not getting the correct measure and may also explain why your strips show nothing (bleached out).  I would not add anything right now.  Your Taylor kit is showing that you have chlorine in the water.  Test free chlorine only with your kit twice a day minimum and track your levels down to zero.  At zero free chlorine, test for total chlorine.  Your readings should be more accurate at that point.

Test strips are generally good for chlorine and not as good for other readings, IMO.  It gives a readable level for chlorine but not accurate enough for pH and TA.

[Vinny]

You can also try this - test the tap water - see if you get chlorine readings, if not procede to:

Take tap water and fill the CYA test bottle to 7 and gently add spa water to get it to 14 (if you overfill you need to start over). Add this to the chlorine test vial and do the test. Whatever the reading is multiply by 2 and that is your chlorine and total chlorine readings. They are approximate but will be close.