Struggling to keep FC up

[duraleigh]

Did you know shocking with chlorine actually can increase inorganic waste?

I don't understand what you mean by "inorganic waste".....can you be more specific?

 

[chem geek]

I know a lot of people here oppose high cya, but a lot of salt water systems require about 60ppm cya!
Getting CAC every night suggests Organic/Inorganic waste. Usually a dirty/older filter media.
Did you know shocking with chlorine actually can increase inorganic waste?! if im not mistaken. There is an article by DuPont about non-chlorine shocks that everyone should read.

If you read Water Balance for SWGs in the Pool School, then you would know that we in fact recommend 70-80 ppm for SWG pools (at least those exposed to sunlight). We are not against CYA, but propose managing the Free Chlorine (FC) level to maintain a consistent disinfection and oxidation rate (roughly proportional to the FC/CYA ratio) as shown in the Chlorine / CYA Chart also in the Pool School.

Shocking does not increase inorganic waste in the long-run. Chlorine in general will temporarily increase intermediate chloramines and the active chlorine level determines the ratio of these. At higher active chlorine levels, one has a lower steady-state monochloramine and dichloramine level, but a higher nitrogen trichloride level while the opposite is true at lower active chlorine levels. Since nitrogen trichloride is very smelly and irritating and can cause health problems, it is better to maintain a lower active chlorine level which is what is proposed on this forum via use of CYA and an appropriate FC/CYA ratio.

A properly maintained residential pool rarely needs shocking. For outdoor residential pools exposed to sunlight, the use of supplemental oxidizers, including Dupont's MPS, is usually not needed. Supplemental oxidation is more appropriate for indoor pools or for high bather-load pools in order to try and reduce disinfection by-products. UV, ozone and MPS are options in that situation as is the use of coagulation/filtration and granular activated carbon (German DIN 19643).