Reliability Of Mps Testing Vs. Chlorine Testing

[ht2020]

On my recent HS Vanguard purchase I was set up with the Nature 2 silver stick/MPS system ie: no or low chlorine recipe. The system is quite easy ie: MPS before and after every soak; shock with dichlor as needed. My only problem with this regimen is that it relies on testing wtih MPS strips to verify that it is being done correctly. Whereas if I use dichlor I can do more accurate testing with a reagent kit (I have the pool master one). Chlorine is easy to test and I suspect that the kits and strips are pretty accurate. Does anyone know if the Zodiac Nature2 MPS strips are accurate? The other thing I can test for with my kit is combined chlorine (test for chlorine first, then wait for 2 minutes and retake the reading to determine the combined chlorine ppm level). I suppose if the combined chlorine is high I can shock as needed.

One other issue: I am shocking weekly with 1oz dichlor and have already done this 4 times. Therefore 4oz of dichlor in a 400gallon pool is equivalent to 36 ppm chlorine and 33 ppm CYA. Therefore, this would indicate that I am now ready to switch to 6% bleach for my weekly shock. How much 6% bleach would I need to use to be equivalent to 1 ounce dichlor? My calcs tell me about 8.5oz??

[chem geek]

The MPS test strips should be OK for their purpose. I'm not aware of reasonably priced drop-based MPS tests except for using the Taylor chlorine tests and then using the K-2042 MPS interference remover to be able to distinguish between chlorine and MPS.

1 ounce weight of Dichlor has the same chlorine content as 8.6 fluid ounces of 6% bleach or 6.25 fluid ounces of 8.25% bleach which is the new standard (Clorox switched last year and most other Ultra bleaches are following).