Simply put there is nothing on the market that is as good as the SeeLevel system. Mine has been working flawlessly for more than five years. Unfortunately I think you're going to have to come to the realization that they were ruined by your cleaning method.
Since you already have the monitor/monitors and wiring installed, I would suggest to just bite the bullet and purchase new tank sensors, and chalk it up as a lesson learned.
I know this isn't what you want to hear right now, but it really is the best way for you to move forward.