Unknow plastic plate in old brine tank

[SLR]

Does anyone know whats this plate for? We found out while we cleaning up the tank and floating inside.

 

[ditttohead]

The salt grids are used in most systems to allow for smaller tanks to be used. Yours is a Chinese cheapy tank, they are used to hold the brine well in place (sort of). Since shipping is everything when getting stuff from China, your tanks is tapered to allow them to be put inside of each other to save container space. That particular brine assembly is a very poor one and should be replaced with either a Fleck or Clack safety float. The tank itself is of acceptable quality. The grid... 50/50.