No free clorine?

[Mosco]

OK I am new here and have been reading a lot of great stuff on this site.
Here is my problem. I have a SWG pool 24' above ground 12000 gal that has been great all summer. Now late in the season I have .5 FC and TC 1.5. Water is perfectly clear so you would not think anything is wrong. I went to the pool store to have water tested to make sure my numbers were correct and they said add 2 lbs of shock. So far I have added the 2 lbs and with in two hours back to .5 FC and 1.5 TC (Per drop test). The next day after reading all the things on this board I added 3 lbs of shock. Two hours later same result. So after using the pool calculator I add 2 gal of 6% bleach, same results. Late last night I add another gallon and call it a night. This morning I check and it looks like both numbers mat be closer to 0 so I hope this might have broken the chlorine lock. I have added 8 cups this morning to see if it will hold at 3 FC. If this does not work I don't know what to do next. Do I keep trying to get the free chlorine to 12 to break the lock or do I keep adding bleach to keep it at 3 until it holds?

After the first day of the 2 lbs of shock I did start to get what looked like residue on the bottom of the pool. Also I have a little brown staining on the bottom of the pool, ladder and at the return. It is not something that can easily be scrubbed off so I do not think it is algae. Not sure if it is a result from where I had to add stabilizer to get my CYA back up from zero a couple weeks ago.


12000 gal above ground
sand filter
SWG
FC .5
TC 1.5
Salt 3000
CH 200
CYA 30
TA 130
PH 7.4
Phosphates 1000

I am currently working also to get the phosphates down as of today.

 

[Bama Rambler]

Welcome to TFP.

What was the shock you added? If it was Dichlor you've added 25 ppm CYA to your pool so now you're at 55 ppm CYA. That's as high as you want to go until you're done with the shock process.

Read how to shock your pool in pool school and follow that until you pass the OCLT. You should use bleach to shock and no more "shock"!

Your shock level now is 20 ppm FC and it would take 4 gallons or 3 large jugs of bleach to get there from zero FC. You'll need to use the Pool Calc to figure exactly how much you need based on your actual test.

If you don't have a good test kit you really should order one.

 

[Mosco]

Thanks for the replay, Yea I will need to have the CYA checked again did not know that the shock would up that.
I will use the pool calculator again to see how much bleach to use.
I am going to use bleach to shock it but my question is do I keep adding the 4 gallons (Pool Calc) until I pass the OCLT and if so do I do that once a day or same as yesterday keep hitting it about every two hours if the numbers are back to .5?

 

[duraleigh]

but my question is do I keep adding the 4 gallons (Pool Calc) until I pass the OCLT

No. You bring the FC back up to the correct shock value by testing the FC and then adding only enough bleach to get back.

read "How to Shock Your Pool" up in Pool School and follow those directions. However, you will need your own test kit to do so,

Save the money you were about to spend on a phosphate remover (which you don't need) and learn how to manage the water on your own without the pool store.

 

[Mosco]

Well you were correct my CYA is now 50 ppm so I will need to shock 20 ppm. The pool store test showed FC 1 ppm and my TC 1 ppm so maybe this is good. If so should I raise my FC to 3 ppm and see if it holds overnight? If it does not hold then I will need to shock according to "How to shock your pool". I have ordered a test kit so I will need to wait for it to get here to be completely accurate. My other question is when I get the pool to hold FC at 20 ppm for the shock process and the total chlorine should also be 20 to 19.5 ppm then I am good to do the overnight test? Should these numbers hold for all day so that my overnight test will be 20 ppm for both FC and TC? If I pass the test and my FC is 19 to 20 ppm the next day how long is it going to take the FC to get back to 4ppm so I can enter the pool?

 

[duraleigh]

Tell me how your water looks currently?

 

[march2012]

Well you were correct my CYA is now 50 ppm so I will need to shock 20 ppm. The pool store test showed FC 1 ppm and my TC 1 ppm so maybe this is good. If so should I raise my FC to 3 ppm and see if it holds overnight? If it does not hold then I will need to shock according to "How to shock your pool". I have ordered a test kit so I will need to wait for it to get here to be completely accurate. My other question is when I get the pool to hold FC at 20 ppm for the shock process and the total chlorine should also be 20 to 19.5 ppm then I am good to do the overnight test? Should these numbers hold for all day so that my overnight test will be 20 ppm for both FC and TC? If I pass the test and my FC is 19 to 20 ppm the next day how long is it going to take the FC to get back to 4ppm so I can enter the pool?

overnight chlorine test is based on shock levels, so raise to shock level and do the test.

during the day you will lose chlorine from the sun 2-3ppm is typical, that is why the overnight test is done overnight. Any FC you lose is from organics.

You can enter the water safely at any point below shock level.

 

[Mosco]

Water is crystal clear. I am going to see if I can get it to hold at 4 ppm today. I just tested it with a DPD and a OTO test kit (new FAS-DPD kit on order) and both showed zero.

 

[duraleigh]

With crystal clear water and your CYA of 50, FC and CC history (assuming it's accurate), I would not be in a rush to shock the pool.

I would CALCULATE (not test) enough FC into the pool to get to about 8ppm. Then, each subsequent afternoon, run your DPD test and take that result (X) and add enough CALCULATED FC to get back to 8ppm.

So, where (X = 3) X + 5ppm (Calculated dose) will get you back to 8ppm each day.

Then, when you get your FAS/DPD test, perform the OCLT test.

YOu may not need to shock at all.

 

[Mosco]

I was able to add enough today to get it to 3 to 4 ppm per my test kit and it has held or maybe dropped only 1 ppm in about 4 hrs of sunlight so I am very hopeful that I have this beaten. I will check it again in the morning to see where I am.
I like your idea of trying to hold 8ppm but with a SWG and a CYA of 50 should I not try and hold 3 to 4ppm per the CYA chart?

 

[duraleigh]

but with a SWG and a CYA of 50 should I not try and hold 3 to 4ppm per the CYA chart

For normal maintenance, yes, but I am suggesting to elevate the chlorine above normal for a few days prior to your anticipated OCLT. It will help get rid of any organics still in your pool and possibly save you the expense of going up to 20ppm and a full shock process.