Gus, the tube in the brink tank should be fine but read the manufacturers instructions. One bigger obstacle to over come and address is how you will retro fit a softener to your home without sending soft water to your drinking.cooking faucets or outside spigots.
Soft Water - It's Not For Drinking You need to inspect your plumbing and determine where to connect the softener which must be prior to the water heater. See if you can supply soft water to the heater and only soft cold to your baths. If you can't find a way then you should consider only softening the hot water. Bathing and clothes washing will still be adequately soft since a majority of the water used is hot.