Does RO/DI water go in my HOB Skimmer?

[Aquaman101]

I just got my Octo Reef HOB skimmer.

The instructions says to fill it up with water to 2-3 inches above the pump.

It's takes several 32 oz. cups to fill it up. Do I fill it up with RO/DI water or with salt water?

Thanks!

[RotaryGeek]

Saltwater. It won't work with freshwater and it will just push it all back into the tank and take out more saltwater anyways. If you fill it up with RO water, you might just drop your salinity.

[vaporlockv2]

+1 to rotary geek