raising SG w/ fish already in tank?

[sooju]

Yesterday I bought a 55G FOWLR tank w/ three clowns and a chromis. I moved the whole tank and got it all set up in its new location with new SW (mixed over the course of the last week). I'm finding that the salinity is a bit low - 1.021 and I'd like to raise it. Can I add a small amount of salt to the 20G sump every couple days until I reach desired 1.023 or 24? Will this affect the fish?

 

[Innovator]

I'd mix in a separate vessel, pitcher perhaps, and slow pour in the sump

 

[roka64]

If it is a FOWLR that is a decent salinity to have. Are you using a hrdrometer? If so, the salinity is probably higher than you think.
On a side note, you should never add salt directly to the tank. You can just add a little higher salinty of pre mixed water when you do your PWC.

 

[Ziggy953]

Good advice all the way around. As roka mentioned 1.021 is fine for FOWLR or FO

 

[catmel]

Yep as others mentioned, good SG for FOWLR ( even with some shrimp etc, no coral) I keep mine between 1.022 and 1.023, everyone seems to be doing well. If its FOWLR a lower SG is easier on the fish. Its also good at those SG because most LFS keep theirs pretty low ( 1.020 and below) and of course with proper acclimation it makes it a little easier for them. Especially if they've been at the LFS a while.

 

[melosu58]

I have to agree also but as mentioned above never add dry marine salt to the tank while it has anything live in it. Do as James said and mix it up first. I like to let mine set 24-48 hrs before I add.

 

[CaPoNe]

I also have to agree, Hydrometers really arent that acurate with measuring the "gravity" id say that anyone in the hobby should look at refractometer. I always used to use hydros until i just had to do a hyposalinity treatment with 5 fish that had ich, and i got the refrac and the hydro was off like .04 each time. So none the less the hypo treatment would not have worked without the refract plus they are just good to have. O and the salinity in your tank is perfect, its higher than its showing so i wouldnt raise.

 

[ccCapt]

Yep as others mentioned, good SG for FOWLR ( even with some shrimp etc, no coral) I keep mine between 1.022 and 1.023, everyone seems to be doing well. If its FOWLR a lower SG is easier on the fish. Its also good at those SG because most LFS keep theirs pretty low ( 1.020 and below) and of course with proper acclimation it makes it a little easier for them. Especially if they've been at the LFS a while.

From the article Reef Aquarium Water Parameters by Randy Holmes-Farley.
"For reference, natural ocean water has a salinity of about 35 ppt, corresponding to a specific gravity of about 1.0264 and a conductivity of 53 mS/cm.
As far as I know, there is little real evidence that keeping a coral reef aquarium at anything other than natural levels is preferable. It appears to be common practice to keep marine fish, and in many cases reef aquaria, at somewhat lower than natural salinity levels. This practice stems, at least in part, from the belief that fish are less stressed at reduced salinity. Substantial misunderstandings also arise among aquarists as to how specific gravity really relates to salinity, especially considering temperature effects.
Ron Shimek has discussed salinity on natural reefs in a previous article. His recommendation, and mine as well, is to maintain salinity at a natural level. If the organisms in the aquarium are from brackish environments with lower salinity, or from the Red Sea with higher salinity, selecting something other than 35 ppt may make good sense. Otherwise, I suggest targeting a salinity of 35 ppt (specific gravity = 1.0264; conductivity = 53 mS/cm)."