The mineral springs unit is a rebranded Goldline/Hayward AquaRite. It uses conductivity to determine salt level and that can change with temperature. The Taylor test is a test for chloride ions. The two will not always agree and can be off by as much as 800 ppm and still be within the accuraly specs of the chemical test and the salt readout on the unit.

The salt levels that the cell is reading is actually more useful since that is what the cell thinks it is. If you dilute and lower the salt level based on the chloride ion test the cell will think the salt is low and can trigger the low salt shutoff. Also, running with lower salt is acutally harder on the cell then running with higher salt.

Finally, the Taylor salt test is very easy to overtitrate. You want to stop at the first color change to red and it takes a bit of swirling between drops to mix everything. You actually want to stop when the color changes from the yellow to a permenant salmon red that does not disappear on swirling. Brick red to brown is actually too far and will give you an inaccurate higher reading.