An overflowing brine tank needs safe isolation and service, not more salt or another forced regeneration. Restricted drainage, failed brine draw and valve or control faults are possibilities in the GE GXSF30V and Fleck manuals. Separate water escaping the tank from a backed-up receiving drain, and document where it begins.
Stop the discharge safely
If you can reach the identified softener bypass or supply isolation from a dry, safe location, use the installed model's instructions. Do not force a valve or disconnect a pressurized hose. If you cannot identify a safe isolation point, ask a plumber for immediate help.
Do not approach electrical equipment standing in water. Keep the area clear and arrange appropriate assistance if the spill has reached electrical parts. Adding salt, scooping out water or unplugging a controller does not by itself correct an uncontrolled water path.
Why the level can rise
GE's GXSF30V high-brine-level table identifies restricted valve-drain routing, incorrectly connected drain lines, and nozzle/venturi problems as possibilities. Its instructions distinguish the valve's regeneration drain from the salt tank's gravity overflow hose.
The Fleck 5600SXT Downflow table lists plugged drain or injector components, a timer that is not cycling, and debris in brine-control components. These are service checks. They do not justify dismantling the valve without the prescribed shutdown and depressurization.
A tank containing some water is not automatically overflowing. For a level that stays contained, see whether water in the salt tank is expected. The cycle phase and exact system matter more than a universal depth measurement.
Check the separate drainage symptoms
If the receiving drain rises during regeneration, use the softener drain-backup guide. If a hose has detached, use the disconnected-drain-hose guide. Do not push either hose into a drain to contain the spill or combine the two functions into one tube.
Report water flowing continuously to the drain as a separate symptom. A control can have a drainage fault even without an obvious display error.
What to give the service provider
Photograph the model label, bypass arrangement, tank level and hose endpoints without moving them. Note whether water rises during fill, fails to fall during brining, or leaks even when the control appears to be in service. This helps distinguish inadequate brine draw from a fill or valve fault.
Also mention a sudden increase in salt use or unexpected salty tap water. After repair, the provider should verify the actual cycle, drainage and treated-water performance before returning the system to normal use.