Pool Chemical Season's Supply

Of course the large season chemical supply saves about $200.00 on the chlorine and shock. I do not really need the large size but the savings, hopefully will make up for it. When you factor in the rain and depending on your areas average rainfall, rain is the worse thing for diluting chemicals in your pool. Most of the time the place that installed your pool has all the chemicals and will test your pool water, they are more expensive and are you sure you can trust what they tell you that you need. Pcpools.coms large supply even beats wal-marts prices, which I found great. I am not sure about the super rust and scale-remover.(?)
I am figuring it works sort of like an algaecide but for rust on pool ladders and scales on the pool liner. I have never had this problem. A lot of people do not know that keeping the water balanced, ph increaser/reducer, or the hardness of the water will cause your pool liner to crack. You would think the 5 and 6 lb. increaser/reducer would be more also instead of the same for all sizes. Hopefully the 5 times more 3" chlorine and 4times more shock will be worth it and keep it up all summer. I still do not want or have never seen any rust or anything that looks like scales in my pool. (Hope I won't need the super rust and scale stuff! I will try to keep posted if my opinion changes.