Yesterday I replaced my SWG and whilst I was at the shop I had my water tested. They used a automated precision pipette to measure water into individual test 'cells' that were pre-dosed with the testing chemical and sealed (obviously this seal was broken to add my pool water). Each 'cell' was then measured in a photometer. I would expect this to be as accurate as testing could be outside of a lab.
the results were :-
This is for a SWG chlorinated pool and I would consider that the CH and CYA should be raised a little
The thing that surprises me (and I dont understand) is how the TC is less than the FC? Surely TC=FC+CC and would always be slightly higher than FC ?
Is this an indication of another problem, a testing error or perfectly normal?