What does code 91 mean on the intex salt water pool system?

Answer 1

Code 91 means your system is reading low salt. This does not mean to add salt, it means to check your salt level of the water (salinity) and to check your system because its major cause is the salty looking crusty crud buildup on one or both ends of the electrolytic plates. That buildup changes the resistance between the plates. The saltwater system uses a range of resistance values to determine the salinity of the water. Since the resistance has been changed, the device "thinks" (used very loosely) the water does not have enough salt, hence the Code 91. So clean the electrolytic plates with some form of acid or white vinegar(your choice) until the plates are shiney again. Do not scrape or scrub the plates as you might scrape off the titanium coating and damage the plates.

I found this other "FIX" on the net ..... Another "CODE 91" fix was said a while back regarding resistors. pull off cover carefully, both the flow sensor and cell power cables exit the case making lifting the plastic case difficult but manageable. look for three adjustable resisters, one above the other. They are marked (or mine was) VR1, VR2,and VR3 on the circuit board. they were black and about the diameter of a pencil eraser with a small Philips (+) adjustable head. The head was locked with glue? but it can be scraped off. The original suggestion said to turn the VR1 resister a quarter turn CCW. This did not work for me but I added an additional quarter turn CCW (now half a turn CCW) and it is back working as it did originally.