I read your article about how to replace resin.
I am in the process of doing it myself but curious why you do not recommend
that tanks under 13" require gravel.
I want to do this right but I am sure that my existing setup has gravel in place.
Thank you for your time with my question.
Less than 5% of residential softeners have gravel in them, and the only reason is to be "different", or in a few cases because the dealer added a cup or two of activated carbon
( waste of time, as too little carbon in the tank to do much for very long ) when "building" the system.
The main problem I have with the use of Gravel ( that is Not needed ) in residential size tanks is the fact that once you have added the Media to the Tank, should you ever remove the Valve from the Tank,
and the Pipe slides up an inch or two ( which is common ) you will NOT be able to put the Valve back on the tank, until you have dumped everything out, put the pipe back on the bottom of the tank, and added the "media" back in.
Having run into this problem a time of two, and the fact that 95% of the units do not have gravel in them is why I recommend that you do not add gravel when replacing the Resin in your water softener.
If you want to add it, it should not "hurt" anything, but since your flow rates in a house peak around 8 gpm, it's a waste of time, money,
and "space" in the tank ( the empty space is for "expansion during the back wash cycle ) to add gravel to the residential size unit.
Resin is fairly uniform in size, and the slots of the bottom distributor are sized to prevent the normal resin bead from getting through these slots.
The resins will only get through if the resin beads have begun to "break down" due to years of exposure to highly chlorinated city water
( at which time pressure will drop as the slots begin to get "clogged" and you would "know" it's time to replace the Resin in the tank, in order to restore normal flow rate through the tank ).
You can replace the distributor tube ( although not normally "Necessary" ) by purchasing a new "bottom" distributor and gluing it to a piece of PVC pipe.
SEE: DISTRIBUTOR - BOTTOM 1.05 O.D. This part combines with a piece of 3/4" PVC pipe( 1.05" O.D. ).
And when you check the resin level in the tank, it needs to be at least 1/2 full ( typically 50 - 65% full ). SEE: RESIN REPLACEMENT GUIDE