The system:
Filtersoft 102-30mp (1990)
Autotrol 460mp control w/2.5gpm backwash valve
10x36 resin tank (13/16 (small) pipe

The water:
28gpg hardness
.9ppm iron (h2s present)
7.1pH
290ppm TDS

The problem:
Though the system has run without fault for almost 23 years, capacity has been noticeably reduced over the years often leaving us with hard water when using the clothes washer. I thought I would give changing the resin bed a try and after a little (maybe TOO little!) research decided to use fine mesh resin due to the iron in our water. I bought 1ft3 of Purolite C100EFM and did the replacement without much difficulty. I re-used the original tube assembly as the slots appear to be pretty darn fine, or are they? I haven't noticed any beads at the taps yet!

When starting the system, I did NOT do anything besides open the valves and run some water (mistake?). The water ran very yellow so I initiated a regeneration (another mistake?). I suspected I was losing resin during the backwash and that turned out to be over 1/2 of it into the sump and out to the ditch!!!

So now I'm looking for some advice as to how to do it properly! Did my improper, or lack of pre-filling the tank cause the loss of resin? Is a filter on the outlet needed? Or even posible on this unit? Is the original filter and pipe ok to use?

While I'm asking questions, I'll ask one about the brine tank - it has no float valve. I was told at the time that the softener only puts enough water in the tank for the next regen, is this true? Do current systems run this way?

Thanks for all help!