Salinity and auto top off

[czcz]

Say an airtight reservoir gravity feeds a sump for auto top off, where the exit pipe drops water into the sump until the pipe exit is submerged. Will it still raise salinity issues with evaporation, since when the vacuum and main is in effect there is one water column? Or can the reservoir be filled with RO/DI, without fear of salts mixing?

The idea for water top off is similar to pouring a bottle of watter into a cup. Water will flow out of the bottle until the mouth is submerged.

Thank you.

[Brenden]

Should not be a issue. It may pull in a little salt but it should not be enough to effect anything and in the end it will be back in the tank. Keep in mind if the top off container is not completely air tight your top off will not work correctly.

[austinsdad]

Be careful of the vacuum effect. When the hose/pipe starts to go down into the sump, have a loose fitting hose or pipe that goes down into the sump. That way, there is no airtight fit and subsequent vacuum back into the reservoir.

See the vertical PVC pipe in the middle of the pic? Look at the red thingy. Just below it there is a 1/2 elbow. It sits on a big hose that doesn't fit airtight.

Now, I haven't run this yet but I'm hoping for two things. 1) no vacuuum sucking my fuge/sump water back into the reservoir, and 2) no water noise from the reservoir water dropping into the fuge/sump. The loose hose sits on the bottom of that chamber.

[czcz]

Thank you both.

austinsdad, thanks for the pic and details of the interesting setup. With the idea in my mind, the airtight seal/vacuum is needed for the pumpless "automated" system. The steps you've taken to prevent water mixing makes me think my idea won't be effective in SW, though I am keeping Brenden's post in mind.

Thanks again,
Joe