Salt levels crash?!?

[Taylor t]

It’s more accurate to use a HIGHLY ACCURATE floating hydrometer with very small increments to calibrate. RO water gets you close, but not accurate on calibration.
Tropic Marin makes a high accuracy hydrometer, it is what I use. Rock solid for years. I use it as the rule of law a couple times a year to adjust refractometers. Treat it with care, mine is a decade old, still very accurate. Store it with care and it will never lie.

 

[OrionN]

Unless you have auto-topoff that mal-function, loss of tank water (or partial obstruction of the overflow which result in higher level of water in DT and lower in sump) with an auto top off that use water level to top off water, you have problem with your measuring device.
I would re-calibrate your equipment now to determine the correct salinity of your tank.
Regardless, you should not mix salt and add salt to your tank. This will cause more damage, even if your tank salinity is low. I would top of with salt water to bring it up gradually.


It is your refractometer and or your salinity probe that is wrong. don't do anything until you confirm the salinity.

 

[iamacat]

your probe is wrong. Did you confirm the probe reading with the refractometer? None of this adds up and you are likely doing way more damage yourself than whatever you interpreted had happened.