Are rodi bad ?

AdamR0331 · Jul 27, 2025

Some Lady told me RODI are bad for reef tanks cause it Softens the water and I will run into issues?????? can someone explain?

fishface NJ · Jul 27, 2025

What! Never heard such a thing. Use tap water then go back to her and buy chemicals to get rid of your problem(s)

Fish Fan · Jul 27, 2025

There must have been a disconnect somewhere. RODI water is too soft for many freshwater fish that do indeed like relatively soft water, but nothing lives in pure water, like RODI water; it's too harsh, water is a powerful solvent when it's pure.

For marine aquariums, we necessarily want very, very hard water, and we get this by mixing very pure RODI water with a salt mix, which makes very hard salt water. The crusty mineral deposits you often see on older or neglected marine tanks is evidence of the hard water, just like hard water build up on your shower head at home.

Long story short, you want RODI water if you want a saltwater aquarium with corals

I hope that helps!

EDIT: Other water options include using distilled water, or purchasing water from a local fish store.

AdamR0331 · Jul 27, 2025

Fish Fan said:
There must have been a disconnect somewhere. RODI water is too soft for many freshwater fish that do indeed like relatively soft water, but nothing lives in pure water, like RODI water; it's too harsh, water is a powerful solvent when it's pure.

For marine aquariums, we necessarily want very, very hard water, and we get this by mixing very pure RODI water with a salt mix, which makes very hard salt water. The crusty mineral deposits you often see on older or neglected marine tanks is evidence of the hard water, just like hard water build up on your shower head at home.

Long story short, you want RODI water if you want a saltwater aquarium with corals

I hope that helps!

EDIT: Other water options include using distilled water, or purchasing water from a local fish store.

Yea she must just be dumb!