What is the lowest salinity possible to keep healthy fish?

[ClarksZ06]

I have a 180 f/o with live rock and I keep my salinity at .021 currently. I have issues with small outbreaks of ich every 3-4 months. If I can keep the fish healthy at a lower salinity like .017 or lower even to help prevent ich I will. I've heard of some people keeping their tank at .013 !! I thought this was crazy but who knows. Does anyone have long term success with lower salinity?

The main tank inhabitants i've had for 2-3 years and include a regal angel, blueface angel, french angel, purple and sailfin tang.

Thanks for any advice.

Clark

[roadracer]

I've heard of it beeing done but unless you are at brackish levels ich will survive & your fish won't long-term. There was another thread here on that & a few of the Moderators agreed there is more harm done than good. Mine is at 1.022 with little ich issues. Is your tank staying a consistant temp? Regular water changes? Overstocked tank? Thats some other facors with ich. If you can keep a cleaner wrasse or cleaner shrimp (depending on inhabitants) it would help alot.

[Qxsilver01]

Do you have a heater in your tank? Whats the temperature f the tank? Whats the temp. of the room?

As for low salt levels, my LFS keeps theres at 1.018. He told me its better to keep it low not becuase of fish diseases, but because it keeps the fishes gills from burning up, and they breath better.

[ClarksZ06]

The temp. in the tank currently is consistantly 80-81 degress. In the summer it runs 81-82. It never goes outside of that range.

As far as water changes go, I do 35 gallon r/o water changes every month and occassionaly 70 gallons at a time. I bring up the alk. to 9dkh, heat the water to 80 degress and let the water mix for a couple days before doing the change.

There is a lot of flow in the tank 2 x rio seio 1500 gph power heads, 2 x maxi jets at 300 gph and a mag drive 950 returning water from the sump.

The fish are perfect specimens, fat and beautiful. I take very good care of them, its just this weird occassional ich that gets old dealing with.