T-15 Cell Types
The Hayward T-Cell-15 and Hayward T-Cell-15-SWP are the same thing.
The T-Cell-15 has a 3 year warranty.
The Hayward T-Cell-15-SWP is a Swimpure branded cell, which has a 2 or 3 year warranty. You would need to verify with the seller to be sure.
The first number of the serial number is the length of warranty.
The TCELL940 is a T-15 "long life" cell with a 4 year warranty.
A T-15-W is a warranty replacement cell with a 1 year warranty. It's not designated as a retail cell. It's supposed to be used as a replacement for a cell that fails under warranty. Some places sell warranty cells as regular cells.
Determining Salinity
The AquaRite uses the performance of the cell to determine salinity. For each cell (T-3, T-5, T-9 OR T-15), Hayward knows the performance of a properly functioning cell at each temperature and salinity combination. The higher the salinity and/or water temperature, the higher the performance (chlorine output).
There is no separate salinity sensor in an AquaRite. There are six wires going to the cell, two white, two black, one red and one blue wire.
The black and white wires carry the power to the cell and are heavier gauge than the other wires. The two white wires go to the center plate. The two black wires tie together and go to the two outer plates. The red and blue wires go to the temperature sensor.
There are no other wires going into the cell to support a salinity sensor. There are 4 extra wires in the cell cord (brown, orange, yellow and green) that are not used and do not go to the cell.
Another way to tell that the AquaRite does not have a separate salinity sensor is that if the T-Cell setting does not match the cell type, the salinity will read wrong.
If the Cell is larger than the T-Cell setting, the salinity will read higher than actual. If the Cell is smaller than the T-Cell setting, the salinity will read lower than actual. One can verify this by changing the T-cell type and see the salinity change.
If there was a separate salinity sensor in the cell, the salinity would not change when the tcell type was changed.
