Am researching on whether to add a sodium bisulfite injection system (pre-carbon tanks) to a water treatment system in order to extend the life of the carbon tanks.
Would appreciate any feedback/risks/concerns on using a sodium bisulfite injection system for this purpose. Thanks

I'll bite. Why? Forgive my ignorance, but carbon tanks are the least of my worries. I'm interested in the pros and cons, as well, but more interested in why to scrutinize one of the smallest hassles, and smallest costs. Knowing little about it, I'd guess it to be more hassle than benefit, but I'll shut up now, and allow someone who knows something to respond!

I am assuming you are not happy with the life of your carbon. Unfortunately, I don't think installing a sodium bisulfite system will increase the life of your carbon. Typically, Chlorine is not exhaust carbon. Carbon catalizes the chlorine to chloride ions. There are numerous sites to catalize chlorine. But, other things in the water, such as organics, coat the carbon blocking the sites to catalize the chlorine. Without other things blocking the sites, the carbon should last a few years. If this is the case, installing an organic filter would work better. Organics in the water also cause the formation of THM (carcinogen) and therefore cause cities to switch to chloramine instead of chlorine injection.