Emergency.

breezey1127

breezey1127

Member
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!
 
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elmafioso52988

Member
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?
 
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elmafioso52988

Member
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

chipmunkofdoom2

Well-Known Member
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! :)
 
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elmafioso52988

Member
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

breezey1127

Member
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
 
chipmunkofdoom2

chipmunkofdoom2

Well-Known Member
breezey1127 said:
Thanks chipmunk (lol) ! That was very helpful
Click to expand...

No problem :)

If you soak your hydrometer for a few hours in vinegar, it should remove the deposits from the swing arm that make it inaccurate.

If you still have the water you drained, you can add it back in. Drastic change will cause the most harm. Your tank inhabitants will bear with you for a few weeks while you get things back in order.
 
breezey1127

breezey1127

Member
Ill clean my hydrometer and compare it to the new one. They are the same hydrometer. I no longer have the water I drain, it goes right down the sink :(.
I suppose I can just slowly add water with the first method you mentioned. It is noisey with the low water level but ill bare with it if it means not causing to much stress on my tank. I wouldnt have drained out so much water if I knew it was so high. I realized after the fact.

I think I need deuce bigalow to come do my tanks from now on
 
chipmunkofdoom2

chipmunkofdoom2

Well-Known Member
Yeah, as long as all your equipment will still run and everything in the tank is still covered by water you'll be fine.

If you added an extra half gallon of fresh water every day, after about 25 days you'd be in the ball park of 1.025. Whichever approach you choose, just give it time :)

Good luck
 
Cloudburst2000

Cloudburst2000

Member
Hydrometers are notoriously inaccurate. They often give bad results because they tend to be cheaply made and the scales are often off. You can definitely use them, but first, it is always a good idea to take them to your LFS or a friend who has a refractometer and compare the results. You can then mark the hydrometer correctly. So the first older hydrometer might be correct, the second one might be correct, or neither might be correct. You can also buy a decently priced refractometer off of ebay as that will definitely be the most accurate way of testing your SG.
 
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