How to automatic mixing water

[sphelps]

Also so if anyone else is interested in another alternative to auto water change without a salinity probe you could setup something like this:

• Two separate top offs will be needed, one for fresh and one for salt.
• The fresh water top off is simply just your standard fresh water top off, set the float switch to trigger at your desired sump level. The only difference is you want the fresh water to be added slowly so use a small pump or restricted pressure/gravity feed.
• The saltwater top off will require a decent size storage tank where you can store premixed saltwater (the same salinity as the display). Install a separate float for the saltwater top off slightly lower than the fresh water float. Just low enough so the saltwater float isn’t triggered from evaporation.
• The saltwater top off should have a fast flow rate so use a decent sized pump.
• Next install another decent sized pump in the sump to remove water quickly for water changes. You can use a timer to activate it or just a switch if you prefer to keep more manual control over the system.

That’s pretty much it. The fresh water top off will replace evaporated water, the slower flow rate will keep up evaporation since this is a slow process. When the pump in the sump is activated to remove water it will do so quickly and activate the lower float switch which will trigger the salt top off. Since the fresh water flow rate is slow the fast saltwater flow rate will top off removed water before much fresh water is added. To make up for the small amount of extra fresh water added during a water change to can keep your salinity a little higher in your make up container. How much higher will depend on your setup and may require a little experimenting.

To limit the size of the container you need for saltwater storage you can try using saturated salt water. You will have to experiment but by placing the saltwater float lower in the sump you can control how much saturated solution is added in comparison to fresh water. You will however have to maintain a constant salinity in the make up container. You can either maintain a high salinity by measuring or you can maintain maximum saturation by keeping temperature consistent and always making sure some salt remains undissolved