A Quick Chem Question

[Dougbyoung]

Is bleach a good oxidizer. And if so what are the parameters? Ie ph,  7-10 x cc, ta levels....

[TdiDave]

Very good, 6.5 to 7.5 pH

[Dougbyoung]

Thanks for the reply. I am having problems decreasing my cc. I will repost later with more info.

[TdiDave]

A shot of MPS may help with the CC

[Dougbyoung]

Ok this will not be as short as I had hoped. First off, thanks for all of previous post. I would not have gotten this far without it.

I have a 450 gal. artesian that I brought 9 weeks ago. I emptied after 5 weeks. I was not intending to empty,  but I could not lower my CC. (increased with dichlor than MPS) I figured  the new spa owner rule was in affect so I emptied. Then I went to dichlor/bleach method. all of my numbers were spot on except CYA @ 40. about a week ago my CC was 1.5 (taylor test and confirmed @ my local spa shop). I used 8 TBL of MPS and the CC did not budge (I now know the MPS give a false reading with the taylor kit). The next day I used bleach 15 oz. I recheck 2 days later FC 2, CC 1.5. I went back to the spa shop for some help and confirmation of my numbers. I was told to add 6 tbl of MPS. After 3 days of the spa not being used and no MPS detected with a strip, my FC was .5 and CC was 1.5. Last night i add 19 oz of bleach. 7 hours later my FC was 6 and CC was 3. 7 hours after that, my FC was 3 and CC was 3. So i just added 8 tbl of MPS. I orderd the K-2041 kit but it won't be here until next week. All I can do is wait until my strips read no MPS then check the CC again

My spa always has a chlorine reading and is crystal clear. I do not think i am underchlorinating.

Thanks for any help in advance.

[TdiDave]

If I understand use are using up over 3ppm chlorine in the second 7 hours and prolly much more than that the first 7?  That seems extremely high, sound like you may have some bug that grabbed ahold.  Maybe try a full decon.
1. Use an enzyme to clean out your pipes, such as Swirl Away, Spa Flush etc. Add this product, run the jets 30 mins and let sit overnight. It will clean out your pipes and deposit the gunk along the water line. Wipe the waterline with a dry paper towel or cloth. Make sure you remove your filter before adding this product. Better yet, buy a new filter.
2. The next day, drain your tub and clean the walls with some leftover enzyme from step one.
3. Refill tub as high as possible (above the normal waterline) with fresh water, and install filter.
4. Balance your water at this point. TA = 80 ppm and pH = 7.2. If your pH is too far out of range, it will decrease the effectiveness of the Chlorine.
5. Add 50 ppm FC using Regular Clorox 6% Unscented Bleach. That's approx. 1/4 gal (32 oz) per 350 gal tub.
6. Run all jets and air features for 30-60 mins. You can turn the air on and off every 10 mins, to help clean the air lines.
7. Cut the power and drain the tub. This water is highly chlorinated, so you may want to keep it away from vegetation.
8. While the tub is draining clean the cover and all shell surfaces with the super chlorinated water. Then rinse well.
9. Refill tub with fresh water.
10. Balance water and try

[chem geek]

For a new spa, I'd use Spa System Flush to get rid of any biofilms and grease.

As for CC, you want to measure the water before your soak, not after, since CC rises after a soak and then gets oxidized away if you are using sufficient amounts of chlorine.

Also note that MPS will register as CC on DPD chlorine tests (in FAS-DPD tests, it measures as FC if there is any actual chlorine at all in the water).  There is an MPS interference remover, Taylor K-1520 for DPD chlorine test kits or the Taylor K-2042 for FAS-DPD chlorine test kits.

[Dougbyoung]

Wow, after a great soak last night I read your post about the bug. Very depressing. However after a little thought, I believe the high chlorine demand was from bather load. I failed to mention I was in the tub with my 10 and 14 y/o daughters for about 2 hours, before i added the 19 oz of bleach. (when they get in demand can be much higher). I soaked again last night with the neighbors. Added the appropriate bleach after our soak  and my numbers were consistent this morning: FC 6.5, CC 2.5, TA 50 and PH 7.2. I am also using a silver cartridge and an ozone.

Although the thought of a bug in my spa was depressing, having the rock star of pool and spa chemistry chime in was great. Chem Geek thanks for posting. My CC numbers are presoak and I have never used Spa system flush. I do have a bottle of Leisure time enzyme. Are those 2 about the same? And would bio film and grease prevent me from lowering my CC?

[chem geek]

Enzymes can work well, though depends on the specific enzymes, but I don't know about any specific enzyme product with respect to biofilms.  The only two products I know do work well based on review of numerous forum reports are Spa System Flush and AquaFinesse Spa Clean.  These products tend to be strong surfactants for dislodging biofilms and breaking up grease -- they aren't generally enzymes.  Most enzyme products are designed to be for helping to break down slow-to-oxidize chemicals, but the other way to handle these (if they don't dissolve well in water) is to coagulate them and catch them in the filter or on a scum ball.