Shock question...

[Gibson00]

So decided to give the tub a shock last night after 4 of us were in for an hour.  I added a heaping cap of 'boost' dichlor powder which should have easily taken me to a 10ppm or more based on past experience and poolmath  (added 25g of dichlor to 360 gallon tub).  I left the cover off and ran jets for about 25 mins.

This morning, about 12 hours later, I measured the chlorine and it was about 1.5 ppm...  So I'm guessing some serious cleaning took place.  Question is, how do I know if the shock actually worked, if the chlorine level got past the breaking point for it??

Thanks!

[Mikedee]

So decided to give the tub a shock last night after 4 of us were in for an hour.  I added a heaping cap of 'boost' dichlor powder which should have easily taken me to a 10ppm or more based on past experience and poolmath  (added 25g of dichlor to 360 gallon tub).  I left the cover off and ran jets for about 25 mins.

This morning, about 12 hours later, I measured the chlorine and it was about 1.5 ppm...  So I'm guessing some serious cleaning took place.  Question is, how do I know if the shock actually worked, if the chlorine level got past the breaking point for it??

Thanks!

25g =.88 oz...On a 365 gallon tub that Free chlorine should be much higher 12 hours later...First I would check your PH level...If that PH level is too high it will reduce the effectiveness of your chlorine for sure..If your PH is in check 7.4-7.8 , then obviously something is eating up that chlorine..( It could be bio-film ) and you would need to purge the plumbing lines...Personally, I'd start with checking the basics, like your alkalinity, PH, etc and get your water balanced..that's important too

[Gibson00]

Really frustrated.

So first, TA = 90 and ph is about 7.6.  They have stayed pretty steady.

Now next thing, I decided to try adding 3 cap fulls (about 60 grams) of MPS to see if it helped clear the water.  Ran jets for 25 mins with cover open.  Weird thing is, after adding that, my cheap test strips still show the chlorine hovering around 4ppm, but the taylor dpd test suddenly shows it up at 9!  It was reading 4 as well before I added the MPS.  Does the MPS interfere with the dpd chlorine test?  If yes, how long before it stops interfering?  2 hours later still the same issue.

ugghhh

[A.O.]

Personally, I would forgo the dichlor boost and MPS and use straight liquid chlorine.