Emergency.

[breezey1127]

Hey everyone. First off i know i should have a refractometer and i am working on that but for now I use a hydrometer. I was getting ready to do a water change the other day and couldnt find my hydrometer so I picked up another one. I am now in the middle of my water change and i found both hydrometers. My old one is pretty dirty... i never realized until now. I tested both hydrometers to compare and my old one is saying my specific gravity in my tank is 1.025 and my new one is saying that it is 1.032. My old one is more than likely the one that is wrong so the last time i didnt a water change i put in way to much salt. Now that im in the middle of my water change how slow do i need to bring it down. How much do i bring it down and how often.
Someone please help!

[elmafioso52988]

how big of a tank?

[breezey1127]

sorry i should have said that. Its a 77

[elmafioso52988]

I would take out 2-3 cups of salt water a day and replace the with fress water. The slower you do it the better. Is anything in your tank looking stress?

[breezey1127]

my fish look fine. My polyps are not happy at all.

[breezey1127]

I have 20 percent of my water already drained out.

[elmafioso52988]

Not much you can do now. Just be patient and dont rush anything. Your polyps will eventually get used to it and go back to normal.

[breezey1127]

So i should just slowly add my water back in. Ill do it over days if i have to lol

[elmafioso52988]

Im not sure what you are asking. Did you already do your water change?

[breezey1127]

Ive drained 20% out of my tank but havent put anything back in yet so my specific gravity is still 1.032

[elmafioso52988]

lol just read your post again. Hydromiter can give you different results depending on which one you use. You cant be sure that any of them are correct. You would have to take your water to a lfs and have them test your salt for you with a refractomiter. Theirs should be correct. You can then mark yours according to their. All hydromiters are different and are just a ball park messurement.

[chipmunkofdoom2]

First thing to do is stay calm. Your tank has been running (probably) for a while like this. Having it run at a slightly elevated salinity while you get things back in order won't hurt things... a large sudden change however will.
If your tank's a 77, that's a good bit of volume to work with. You'll need to bring it down gradually over time.

To figure out what your water will be after a water change of different salinity, simply do the following:

(Volume of water changed x salinity of water change) + (volume of tank water x salinity of tank water)

Divide that number by total water volume and you get ending salinity.

For example, say your tank holds 70 gallons total and you do 25% water changes (about 17 gallons)...

17 x 1.025 + 53 x 1.032 = 72.121 / 70 gallons = 1.030

17 x 1.020 + 53 x 1.032 = 72.036 / 70 gallons = 1.029


You could use this formula and gradually keep reducing the salinity of the makeup water to lower the overall SG, but it would be a long tedious procedure.

I'm not sure how you do your top-offs, but another alternative would be removing a gallon or so of saltwater every day and replacing it with fresh water.

To figure out your salinity change from this:

(Tank volume - fresh water to be added) * salinity + fresh water to be added / total volume

So, if you were to replace one gallon of saltwater with freshwater:

(69 * 1.032) + 1 = 72.208 / 70 = 1.0315

I would opt for the second method here. Much less saltwater wasted and much smaller changes.

Good luck!

[elmafioso52988]

Just go by your old hydromiter because at lease your mesurement of salinity will be consistent to that hydromiter. If you use the other one you might increase of decrease the salinty drastically. Use your old one and go by that.

[breezey1127]

I wish I could! There isnt even a lfs around here that uses a refractometer.. isnt that helpful? But i bet my school has one. Ill see if they can test my water. Thanks for your help

[breezey1127]

Thanks chipmunk (lol) ! That was very helpful