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auto top off setup help
Posted: Mon Sep 22, 2025 5:17 pm
by leestone
I'm setting up an auto top off for my 75 gallon saltwater tank and could use some advice. I've got a Tunze Osmolator but I'm not sure about the best placement for the sensor. Should it go in the sump or the display tank? Also, any tips on avoiding overflows?
Re: auto top off setup help
Posted: Mon Sep 22, 2025 7:15 pm
by greenspark
Place the sensor in the sump, mate. That's where the water level fluctuates the most. Make sure it's away from the return pump to avoid false readings. For overflows, set a backup float switch just in case the primary fails. I've been running this setup for years with zero issues.
Re: auto top off setup help
Posted: Mon Sep 22, 2025 10:13 pm
by tamilian_7
Yo, I've got the same Tunze Osmolator. Stuck the sensor in the sump like greenspark said, and it's been chill. Just double-check the wiring, though. Had a sketchy connection once that messed with the readings.
Re: auto top off setup help
Posted: Thu Sep 25, 2025 5:27 am
by polar
greenspark wrote: ↑Mon Sep 22, 2025 7:15 pm
Place the sensor in the sump, mate. That's where the water level fluctuates the most. Make sure it's away from the return pump to avoid false readings. For overflows, set a backup float switch just in case the primary fails. I've been running this setup for years with zero issues.
Totally agree with this. I'd also add that you should test the system with fresh water first to make sure everything's working before you hook it up to your tank. Better safe than sorry, right?
Re: auto top off setup help
Posted: Thu Sep 25, 2025 10:49 am
by Elpenz
Anyone know if the Tunze Osmolator works with a 40 gallon breeder? I'm thinking of upgrading my setup but wanna make sure it's gonna cut it.
Re: auto top off setup help
Posted: Thu Sep 25, 2025 11:06 am
by leestone
Thanks for the tips, everyone. I'll try the sump placement and test it with fresh water first. Appreciate the help!
Re: auto top off setup help
Posted: Thu Sep 25, 2025 3:00 pm
by greenspark
Elpenz wrote: ↑Thu Sep 25, 2025 10:49 am
Anyone know if the Tunze Osmolator works with a 40 gallon breeder? I'm thinking of upgrading my setup but wanna make sure it's gonna cut it.
Yep, it'll work fine. Just adjust the sensor sensitivity to match the smaller volume. The Osmolator's pretty versatile.
Re: auto top off setup help
Posted: Fri Sep 26, 2025 9:21 am
by polar
Another thing to consider is the evaporation rate. If your tank's in a dry area, you might need to top off more often. I've got mine in a humid room, so it's not too bad.
Re: auto top off setup help
Posted: Fri Sep 26, 2025 9:34 am
by tamilian_7
True that. My tank's near a window, and the evaporation's wild. Had to tweak the sensor a bit to keep up. Still, the Tunze's been solid.