Arduino Saltwater Chlorine Generator, intex

New to arduino and curious on the hardware needed to replace the intex eco5110 cg-28667 board with something not using high salt alarms.

Original Post from 2010.

I see nothing about the hardware side, but the software side is there.

What hardware would I need, and any tips on how to accomplish this?

If the existing controller board is still functional then it would appear that you just chop out the existing microcontroller and tap into the logic level control lines that activate the relays, read the switches and drive the displays.

The existing board has a problem with high salt when it's fine. I was wanting to completely bypass the current board.

traustic:
The existing board has a problem with high salt when it's fine. I was wanting to completely bypass the current board.

Bypass the alarm or bypass the board?

To bypass the alarm, if the high salt alarm is software controlled then you can choose to omit that functionality in your drop-in replacement Arduino code.
If the high salt alarm is a hardware interlock then you'll need to repair the board or modify it to disable the alarm.

To bypass the board completely then you'll need to build a whole new board based on the design goals of the original.