what's the difference between fiberglass vs mineral tank? I see different vendors supply these 2 tanks as 12 x 48 and 12 x 52 for 64k grin system.

In additon: My current setup were using 3/4" piping. I could have using the flex connectors for easy installation, but I'm worry the 3/4" piping will limited the water flow rate.

The main piping to house were 1.25". Should I re-piping to 1" pipes instead? I'm about the purchase the softener, but needs the info before I order the system.

Maybe I should have giving more infor:

My current water softener is a GE Smartwater Profile 40k system with 1" male threads. Somehow the installer has using the 3/4" copper pipes to connect between softener and house's main 1.25" pipes. I can feel the water pressure drops when 2 showers run at same time. This has bothering me the last 10 years.... Finally the water softener broke down!!!

Now, it is the chance to correct all the problem. It is good that I have decided on the Fleck 7000 64k system. I don't mind to hire a professional to install the system, but I need the info on correct size bypass connection to get with the new softener.

As I mention ealier, I can use a flex connector for simple installation over the exiting 3/4" piping, but I don't want to face the same problem I had for last 10years. Will a 1" piping helps? Or stay with 3/4" piping since the Fleck 7000 has better internal high flow valves compares with GE?

many thanks in advance