Jump to content

CC off the charts


Recommended Posts

First of all, thanks for making this such a great resource. Our salesman told us nothing about water chemistry when we bought our new PDC Spa a couple months ago. I've learned everything I know about water chemistry on this forum.

Here's my issue. After a totally failed first fill that resulted in foamy water after about three weeks. I started with a fresh fill a couple of weeks ago. Got TA and pH into acceptable ranges and begin using dichlor to sanitize to roughly 3ppm after each soak. I should point out our spa has an ozinator. This was going well until I learned about the bleach method and realized my CYA at that point was over 100. I drained the tub down some and added fresh water to get CYA ~80. Even though I know that's an elevated CYA level for the bleach method, I started using bleach instead of dichlor. That was going well too until I realized my CC levels were waaaaay out of acceptable range. I'm talking in the 10ppm range when tested on my Taylor 2006 kit. 

I've tried adding MPS, leaving the cover open in sunlight, super chlorinating with 2.5 cups 6% bleach, and nothing has worked to get those CC levels down.

I have two questions: how do I get CC levels down and is it safe to use tub with levels that high? I'm hoping I don't have to drain and refill...

EDIT: I should have added that the water is clear, I don't have significant foaming, and I'm not smelling noticeable chloramines 

Link to comment
Share on other sites

1) please post a FULL set of test results

2) if your CYA is 80 ppm then you need to maintain a FC level of 6-12 ppm for NORMAL chlorination and would need to shock to 20 -25 ppm. If you have not been maintaining these FC levels there is a good chance that there could be a biofilm buildup in the plumbing. contributing to the persistent CC.

3) are you using a 10 ml sample or a 25 ml sample when testing FC and CC and exactly how many drops of the FAS titrant are needed to change the color from pink to colorless for each titration?

Link to comment
Share on other sites

7 hours ago, waterbear said:

1) please post a FULL set of test results

I just took a fresh set of readings. They are as follows:

pH: 8.0

TA: 80

CH: 170

CYA: 50

FC: 0.5

CC: 6.5

7 hours ago, waterbear said:

2) if your CYA is 80 ppm then you need to maintain a FC level of 6-12 ppm for NORMAL chlorination and would need to shock to 20 -25 ppm. If you have not been maintaining these FC levels there is a good chance that there could be a biofilm buildup in the plumbing. contributing to the persistent CC.

My understanding was by adding the 2.5 cups of 6% bleach I would exceed 25ppm. Do I have that wrong?

7 hours ago, waterbear said:

3) are you using a 10 ml sample or a 25 ml sample when testing FC and CC and exactly how many drops of the FAS titrant are needed to change the color from pink to colorless for each titration?

I'm using 10ml given the high CC present. This most recent test required 13 drops to turn from bright pink to clear.

After my first failed fill I used a product from Marquis called "jetline cleaner" It came in the box of stuff from the salesman. I followed the label's instructions. As far as I know my FC has never dropped to zero on this most recent fill. I want to emphasize that I have an ozinator. I'm still learning how that affects my FC levels. Thanks for your help!

Link to comment
Share on other sites

FC .5 and CC 6.5 means that there are organics or biofilm in your tub. are these results after shocking or after the tub has been sitting? If the CC is that high after shocking I would try purging. This condition probably occurred because of under-chlorination  when your CYA levels were high combined with the ozone destroying what little chlorine was being added that allowed stuff to 'grow' in the tub.

As far as how much 2.5 cups of 6% bleach will raise FC, it depends on the volume of water which I did not see in your posts, In a 500 gal spa it will raise FC by 19 ppm. In a 350 gal spa, 28 ppm.

Link to comment
Share on other sites

@waterbear, thanks for the reply. You nailed it. I did a purge with ahh-some, and completed Nitro's decontamination procedures. Based on the green substance that floated to the surface during purge I think you're spot on about the under-chlorination.

I've refilled after the decon procedure and I've now added 33ppm dichlor over the course of a week and a half or so. The water seems to be testing great. Just checked it and I'm at 4.5ppm FC and ~0.2ppm CC. So I'm happy with where I'm at. I think I'm ready to switch to bleach. I should have 30 ppm CYA at this point. However, when I test using my Taylor 2006 I get all the way to the top of the small comparator tube and can still clearly see the black dot. Indicating I'm at less than 30ppm CYA. 

Is it possible the ozonator is reducing the CYA? Should I go ahead and switch to bleach now based on my CYA estimation or wait until I test 30ppm on the test kit?

My tub is 325 gallons.  

Link to comment
Share on other sites

14 hours ago, joe_blow said:

Is it possible the ozonator is reducing the CYA?

not to the best of my knowledge.

 

14 hours ago, joe_blow said:

or wait until I test 30ppm on the test kit?

I would wait for the test to indicate that you are at 30 ppm. lAlso, you want your water sample to cool to room temperature before testing CYA, shake the bottle for about 20-30 seconds, let it sit about 5 minutes, shake again and then test. Give it a try and see if you get different results on the CYA test.

Link to comment
Share on other sites

9 hours ago, waterbear said:

I would wait for the test to indicate that you are at 30 ppm. lAlso, you want your water sample to cool to room temperature before testing CYA, shake the bottle for about 20-30 seconds, let it sit about 5 minutes, shake again and then test. Give it a try and see if you get different results on the CYA test.

I retested using this technique and it was noticeably "cloudier," making me comfortable that I'm actually closer to 30ppm CYA. I could still see the dot so I may add another 3-5ppm dichlor and retest.

Thanks for the guidance.

 

Link to comment
Share on other sites

14 hours ago, waterbear said:

check out the photos at the end of this Taylor tech tip. It shows what the CYA test should look like when the dot disappears.

https://www.taylortechnologies.com/en/page/171/why-monitor-cyanuric-acid

 

Thanks! Adding 3ppm dichlor still doesn't give me the result in the linked picture. I might have to add 3ppm more. That would be a total of 39ppm dichlor. Any idea why I'm not getting the same 10/9 dichlor/CYA relationship? It's my first time using this method after two failed fills so I'm worried about messing it up again.

Link to comment
Share on other sites

Please post the ingredients and the brand of your dichlor. It is 99% dichlor with with 56% available chlorine (which is what you want) or does it list something like:

SODIUM DICHLORO-S-TRIAZINETRIONE 58.2% 

OTHER INGREDIENTS listed as 41.8%

which is not what you want since it's only about half dichlor.

Link to comment
Share on other sites

21 minutes ago, waterbear said:

Please post the ingredients and the brand of your dichlor. It is 99% dichlor with with 56% available chlorine (which is what you want) or does it list something like:

SODIUM DICHLORO-S-TRIAZINETRIONE 58.2% 

OTHER INGREDIENTS listed as 41.8%

which is not what you want since it's only about half dichlor.

It is "HASA" brand.

SODIUM DICHLORO-S-TRIAZINETRIONE 98%

Other Ingredients 2%

Available Chlorine 56%  

Link to comment
Share on other sites

Are you using a K2006 or a K2005 for testing? IF you are using a K2006 are you using a 10 ml or a 25 ml sample for FC tests?

If you have added a total of 33 ppm Free Chlorine cumulative. (For example, you initially shock to 15 ppm, chlorine drops to 5 ppm, you then add enough dichlor to bring the free chlorine up to 10 ppm which means you have added an additional 5 ppm for a total of 20 ppm cumulative (initial 15 ppm and additional 5 ppm). You then wait and FC  has dropped to 2 ppm so you add dichlor to raise it to 6 ppm which means you have added an additional 4 ppm FC to raise the 2 ppm to 6 ppm for a cumulative total of 24 ppm. Next test your FC has dropped to 3 ppm so you add enough dichlor to bring it to 6 ppm which means you have added 3 ppm for a total of 27 ppm FC cumulative. Next test your FC is at 4 ppm so you add enough FC to bring it to 10 ppm which means you have added 6 ppm FC for a cumulative total of 33 ppm FC added. Your CYA should be right around 30 ppm at this point. The CYA scae on your comparator is logarithmic and not linear so ther is some margin of error. IF you have not made an error in your totaling of cumulaitive free chlorine added then you should be in the ballpark of 30 ppm CYA and I would not lose any sleep over it. A common mistake is to simply test the FC affer addition of dichlor and forgetting to subtract the initail FC reading to get the amount of FC added. This requires testing FC both before AND after addition of dichlor.

When you do the CYA test hold the comparator at waist height and stand in open shade outdoors (best) or indoors out of direct light as you slowly add the sample to the tube. Don't stand in direct sunlight or near a bright light source indoors. You want indirect light to read a turbidity (cloudiness) test.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
×
  • Create New...