You should have told them what size tank, and they should have asked you what size tank.
Call them and tell them a 9" x 48" (1.0 cuft) and what type resin you have and have them send you what DLFC and BLFC you need for the valve they sold you.
Before you call them, check the level of the resin in the tank is about 15" down from the bottom edge of the dome on top the tank; that's where the straight side starts to curve.
In the dark, hold a light against the side of the tank away from the side you are looking at and look for the light to stop showing through when the light gets down to the level of the resin.
If the tank wont allow light through it, then you have to take the valve off without breaking the distributor tube. Then the DT must be back down touching the bottom of the tank with no gravel etc. under it before screwing the valve back on. Lay the tank down after pouring the water out and lift the bottom and shake it to make the resin all lay on the bottom of the side and put a finger in the end of the DT and put the DT in the tank without 'plowing' resin (hold it up against and slide it along the top side of the tank) until the point of the DT gets into the dimple in the bottom of the tank.