Test Strips

[vincent]

Does this only happen to me

FC level in spa .05, add 2 tbls Potassium peroxy- monosulphate FC level goes up to 2.6 bromine goes from 0 to 3ppm

I thought this was supposed to be a chlorine free shock ?

[quantumchromodynamics]

First of all, stop using the test strips. Get a good test kit.

If you are using chlorine, get the Taylor K-2006 as shown here http://www.taylortechnologies.com/products...&KitID=2230

The test kit comes with a very good book about water chemistry. Also, get KIT NUMBER: K-2041

http://www.taylortechnologies.com/products....asp?KitID=2265

The K-2041 kit includes a monopersulfate interference remover and a test for monopersulfate. The monopersulfate will interfere with the chlorine test.

If you are using bromine, the monopersulfate will convert inactive bromide ions into active bromine. If you have bromide ions in your water, any active chlorine will oxidize the bromide ions into active bromine. If you are using bromine, get the Taylor K-2106 as shown here

http://www.taylortechnologies.com/products....asp?KitID=2232

[chem geek]

Non-chlorine shock (MPS) will show up as Combined Chlorine (CC) and in high enough levels and in some tests as Free Chlorine (FC) so that is why it showed up in your test strips -- it's basically interference and yes, this is known and common. As noted in the post above, the higher quality test kits have an interference remover.