How to automatic mixing water

[donlite]

In the end all I used was 2 aqua lift pumps and a 30 gallon tank from coke. The salinity is dead on. They turn on for a few minutes every hour and thats it. I have to use 2 pumps because if I drain first the 3rd aqua lift pump (for water top off, fresh water) will start up.It works very well but make sure the tubes do not fall out of the tank. I water top offed my floor for about 2 hours