Eliminating CC

[J24]

What else should I do to eliminate the CC's in my tub?

Initial test results 11/14 @ 2pm:
FC: 2
CC: 3 (calculated)
TC: 5
pH: 7.5
CYA: 48
TA: 50
CH: 200
Borates: 43 (calculated)
355 gallons
Leslie Complete Kit (Taylor chemistry)

Shocked with 10 oz of Clorox (14 ppm) hoping to eliminate the CC's


Follow up test results 11/15 @ 10am
FC: 3
CC: 1
TC: 4
pH: 7.5

Not happy with the lingering CCs.
Bumped the FC up to 5ppm with 1.5 oz of Bleach (target level)
Added 2.75 oz (weight) of MPS as an additional oxidizer to see if I could help knock out the remaining CC.

Comments / advice appreciated.

Planning to soak tonight.

Need a better chlorine test -- the drop / color block test in Leslie's kit goes up to 5 ppm and it isn't very exact. I dilute the sample 50% to get a wider range, but I think it impacts the accuracy.

Thanks

 

[J24]

Re: Elminating CC

Quick follow up...

Once I added the MPS, I turned the jets and air on high and within 15 minutes a massive sticky scum line formed around the shell at the surface. I assume that is the MPS doing its thing.

How do you get the scum line off without adding things to the water that will mess up the balance?

 

[Bama Rambler]

Re: Elminating CC

Here's what Chem Geek said about MPS reading as CC.

Yes, by non-chlorine shock I mean potassium monopersulfate (MPS). Unfortunately, the MPS itself will usually register as CC in the chlorine test -- very high levels, especially soon after addition, can also show up as FC. There is a Taylor K-2042 kit to remove the MPS interference, but this isn't always reliable. The MPS may not get rid of the CC either, but it's something you could try (see what happens after the chlorine level comes back down -- that is, is the CC still there and does it still smell).

Sounds like that may be what you're seeing.

 

[chem geek]

Re: Elminating CC

Measuring CC shortly after a soak will be normal as the chlorine combines with the ammonia (ane urea) from your sweat and urine. This usually breaks down within an hour or so. Were you measuring CC at the start of your soak? Also as noted above MPS will measure as CC. Are you using the Dichlor-then-bleach method?

It isn't normal to get such as scum line so readily after using an oxidizer such as MPS. By any chance, is this a newer spa? If so, did you use Spa System Flush to initially clean out the chemicals and biofilm typically found in a new spa? With a new spa, one usually needs to replace the water sooner from that first fill; after that, it lasts much longer.

 

[J24]

I measured CC at least 36 hours after the last soak and 20 hours after shocking to 16 ppm chlorine.

It is a new spa. The water and spa are 2 weeks old. Sounds like a drain and flush may be in order.

I checked again at 5pm and:

FC: 1
TC: 4 (but this may be reading artificially high due to the earlier MPS shock)

I am going to boost the FC back up to the target of 5ppm (according to the CYA/FC chart) and check the CC's again tomorrow.

 

[frustratedpoolmom]

I agree with Richard, since the spa is new I would drain and refill.

Also you can order an fAS-DPD chlorine test to supplement your current kit, separately from both Taylor and TFTestkits. It's a drop-count test, not color matching - you will like it much better. Sells for about $25 but worth every penny.