My experience using chlorine (12% bleach) is that water with a pH above 8.4 it loses its effectiveness.  Storage of liquid chlorine also tends to reduce the strength due to de-gassing of the solution. Use of a solid slow dissolving tablet form may be desirable. Bromine/chlorine tablets or a stabilized liquid bromine may be preferable at higher pH conditions. Continuous feed will be more effective than shock feed; generally 0.5 to 2.0 ppm of using a DPD test kit should provide good control. It also will reduce potential addition of chlorides. Weekly "shock" addition of a non-oxidizing biocide will improve algae control as well. Chlorine dioxide is a very effective biocide in penetrating biofilm which is the foundation for algae growth. However it has be very short shelf life ater production which means it is best to make it on site. It is best to be fed within hours of its generation. My experience is that it degasses very easily. Control levels are in the ppb range but testing in the field is difficult. It will not contribute cosiderable levels of Cl.  Regarding stainless steel tubes, if they are SS 316 or higher, many metalurgist feel chlorides are not a concern unless the metal has been stressed due to poor quality welding or bending. However SS 304 can be penetrated by Cl at >50 ppm.

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My experience using chlorine (12% bleach) is that water with a pH above 8.4 it loses its effectiveness.  Storage of liquid chlorine also tends to reduce the strength due to de-gassing of the solution. Use of a solid slow dissolving tablet form may be desirable.

Bromine/chlorine tablets or a stabilized liquid bromine may be preferable at higher pH conditions. Continuous feed will be more effective than shock feed; generally 0.5 to 2.0 ppm of using a DPD test kit should provide good control. It also will reduce potential addition of chlorides. Weekly "shock" addition of a non-oxidizing biocide will improve algae control as well.

Chlorine dioxide is a very effective biocide in penetrating biofilm which is the foundation for algae growth. However it has be very short shelf life ater production which means it is best to make it on site. It is best to be fed within hours of its generation. My experience is that it degasses very easily. Control levels are in the ppb range but testing in the field is difficult. It will not contribute cosiderable levels of Cl. 

Regarding stainless steel tubes, if they are SS 316 or higher, many metalurgist feel chlorides are not a concern unless the metal has been stressed due to poor quality welding or bending. However SS 304 can be penetrated by Cl at >50 ppm.

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SS 316 can tolerate chloride upto 1000 ppm (and some time in running seawater) however; these are when SS 316 is in an oxidizing atmosphere but under reducing conditions such as biofouling/fouling etc chloride tolerance is lower. Most of the cases are those where water has remained stagnant and biofouling has taken place. 

 

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