Salinity help

SGT · Oct 11, 2016

I am still pretty new to the saltwater tank hobby. So have had my tank for about 6 months, everything good. I checked my salinity after a water change over the weekend and it was around .016. Added more salt a little at a time to the point it should go back to where it should be. I even changed out my hydrometer and not much boost. Now I've lost an arrow crab. I'm parnoid that my salinity is too high yet it's reading low. Does it take time to raise the level or is something else wrong?

rvlcf · Oct 11, 2016

Get a Refractometer and calibration fluid. Hydrometers aren't as accurate. Make salinity changes slowly.

Stirfry · Oct 11, 2016

1.024-1.025 was what I've been told is a good place to be at. The LFS explained that water top offs should be done with freshwater to not go overboard on salt as only the water evaporates. Top off with salt water to slightly increase salinity over time.

SGT · Oct 11, 2016

rvlcf said:
Get a Refractometer and calibration fluid. Hydrometers aren't as accurate. Make salinity changes slowly.

Okay. Thanks for the reply!

Paula C Owens · Oct 11, 2016

I'm also new to saltwater and working on raising salinity levels on our 150 gal. It's been suggested to me that I drain and add salt to that existing water then check salinity of that water and add it back directly to the tank. Also been told to only add freshwater into the sump because the water will evap but the salt doesn't evap. Good luck and hope this helped!!!

amazonjoe · Oct 11, 2016

How big is your tank and do you have a sump?

amazonjoe · Oct 11, 2016

When I mix salt, I use a measuring cup. This way I'm consistent. I use an extra powerhead to mix it in a bucket. I measure about 30 min to an hour so the salt mixes well

SGT · Oct 11, 2016

amazonjoe said:
How big is your tank and do you have a sump?

It is 37 gallon and no sump. LFS said that the very little amount of fish in there don't need a sump however if I get a few more I will need one.

SGT · Oct 11, 2016

Paula C Owens said:
I'm also new to saltwater and working on raising salinity levels on our 150 gal. It's been suggested to me that I drain and add salt to that existing water then check salinity of that water and add it back directly to the tank. Also been told to only add freshwater into the sump because the water will evap but the salt doesn't evap. Good luck and hope this helped!!!

I did everything as I did before considering water changes in the past and all of a sudden the salinity is way off. The salinity always changed immediately now it seems that it goes up by just a small amount the next day. I am adding gradually and I may take some down to the LFS and have them test it again.

amazonjoe · Oct 11, 2016

Are you using a refractometer or a hydrometer. Refractometer are more reliable.

SGT · Oct 11, 2016

amazonjoe said:
Are you using a refractometer or a hydrometer. Refractometer are more reliable.

Hydrometer. I don't think my LFS seems the refractometers.

Salty1962 · Oct 11, 2016

If you don't have a refractor to measure your salinity, go to your LFS and have them test it. I would bet that your salinity is still a little low for a crab to die. As mentioned slowly add saltwater back, just @ 1.030, as your water change and keep testing. Go slow and get yourself a refractor for future measurements. Swing arms are NOT an accurate means to measure salinity, too many factors can influence the accuracy of them

Duke4Life · Oct 11, 2016

When I check mine monthly I'll sometimes get my old hydrometer out and play. Comparing readings between my hydrometer and refractometer is very marginal, maybe .02 or .03 of a difference.

SGT · Oct 11, 2016

SGT said:
Hydrometer. I don't think my LFS seems the refractometers.

I also had them test my water down there and the levels matched to what my readings were so I'm confused as to why it's not raising. I'll have to order a refractor online.

melypr1985 · Oct 11, 2016

Are you adding salt to the tank? Or saltwater? You want it to go up only a little at a time.... make it slow. Topping off with saltwater instead of fresh will get it back up over the course of several days. This is a very safe way to do it, but it does take time.

MasterBacon · Oct 11, 2016

What is your current reading on salinity via the swing arm?
Tank &
Saltwater used to top off

SGT · Oct 11, 2016

MasterBacon said:
What is your current reading on salinity via the swing arm?
Tank &
Saltwater used to top off

.019 is what it's reading. Its going up now. Maybe I was just being paranoid. I just remember doing water changes in the past that it was almost instant. I'm just adding a little at a time, maybe a little less than 1/4 cup salt. I don't buy the premade saltwater just RO. I am definently going to look into a refractometer though.

SGT · Oct 11, 2016

melypr1985 said:
Are you adding salt to the tank? Or saltwater? You want it to go up only a little at a time.... make it slow. Topping off with saltwater instead of fresh will get it back up over the course of several days. This is a very safe way to do it, but it does take time.

I add Salt to RO water

melypr1985 · Oct 11, 2016

SGT said:
I add Salt to RO water

Oh Whew! I'm glad. I made that mistake about 10 years ago when I first started out. It kills me today to think about it and what I did to those poor fish. Anyway! The fact that your adding a very small amount at a time, the salinity will raise very slowly as well. Also, it will take time for that small amount to work it's way around the tank and mix in thoroughly. So, you add a 1/4 cup and wait about 30-45 minutes before taking a measure. You wont see a lot of difference (if anything) with a swingarm though, with each 1/4 cup. It would take a few for a swingarm to register it, I'm sure