Salinity for FO Tank

[btkrausen]

I've been doing reef for a long time, but my new 220 will be FOWLR. What are you guys keeping your FO salinity at?

What are the added benefits besides using less salt Does it help with disease control better than a higher specific gravity?

Thanks in advance.

 

[Jerry W]

IMO, the only reason to maintain a lower salinity is to save on salt. To combat diease, you need to be in hyposaline conditions. Anything higher does nothing. I ran my FOWLR tanks at NSW levels; 35-36 ppt.

 

[dzfish17]

One of things Ive heard is that lower salinity allows more oxygen into the water. You'll need a smarter member than me to elaborate on this though. I run my FO at 1.022/23.

 

[btkrausen]

Thanks guys. I might run it a little lower just to save on salt if it doesn't hurt anything. This tank will eventually be a reef probably, so I won't run it too much lower.

 

[Reefman29]

I keep both of mine at 1.018 to 1.019 and never above 1.020. It saves salt and helps with oxygen and that can help with diseases since the fish breathe easier.

 

[Wolverine]

I keep both of mine at 1.018 to 1.019 and never above 1.020. It saves salt and helps with oxygen and that can help with diseases since the fish breathe easier.

Back when we had a few FO tanks, I ran them in that range, but mostly to save on salt. I'm not convinced it makes a significant difference in disease; as Jerry mentioned, you're not at true hypo at this level.

 

[btkrausen]

Thanks. I assume there is no harm to fish in whether they live in 1.018 compared to 1.025?

 

[kirkaz]

I also think fish are more active at lower salinity. More oxygen I suppose, but it is easier to swim in lower salinity....Try swimming in the Dead Sea.

I kept my FO I used to have at 1.019.

 

[Recty]

The benefits of lower salinity, as I understand it...

Lower salt in the water means it can hold more oxygen... the same applies to cooler water.
Lower salt means the fish have to work less to maintain their proper internal salinity.
Lower salt is cheaper to maintain/mix/replace.

For those three reasons alone I keep my salinity around 1.019 now... but if you're going to have inverts I wouldnt go much below 1.022. I plan on getting a couple cleaner shrimp soon and I will probably raise back up to around 1.022 at the time.

 

[Wolverine]

Thanks. I assume there is no harm to fish in whether they live in 1.018 compared to 1.025?

For most fish that's true. There are a few less hardy fish that don't tolerate it well, but they're the kind of fish that you should be researching pretty intensely before you buy anyway, so you'd find that out.

 

[MrTuskfish]

Another line of reasoning for keeping fish at a lower SG was that the water was lighter, thus easier on the fish. Fish not only have less resistance when they swim, they have less inward pressure on them. May sound silly, but makes some sense. I kept fish, as did many hobbyists at 1.017 for many years with no obvious problem. I still keep my fish at a lower SG (1.018 now) than most folks. Salt cost and parasites aren't a concern; I'm just convinced that many fish, especially large ones, are more active at this level.

 

[namxas]

Everyone is making valid points, and FWIW, we run all 13 of our FO setups right around 1.019-1.020.