First off I would not use Eco-Matic brand, They have to many problems and the mother company Balboa has no competent tech personel and they do not stand behind their salt equipment. Now to answer your question. The only way to remove TDS is to drain, adding salt will contribute to TDS.The most important factor with any system is chain of command in your pool, # 1 Alkalinity which controls PH which controls chlorine activity. # 2 CYA or stabelizer which when used properly controls chlorine consumption. # 3 Salt systems are inhibited by phosphates from producing properly. salt systems make chlorine by seperation, occasionally you should add a considerable amount of fresh water to your pool to freshen it up weather by backwashing frequently do a partial drain as done in the freezing states to winterize a pool. This is probably not a good idea. The TDS reduction system will be taking salt out of the pool water which the the salt system needs to make chlorine. If the salt level in the pool goes to low it will be bad for the cell. The low salt level will shorten the life of the cell and it is the most expensive parts to replace on the system usually 500-600 dollars. So I would say not a good idea.