Salinity and water evaporation

wigwam · Jan 31, 2016

I have a 40 breeder with salinity at 1.023. What will my salinity be if 1 inch of water evaporates? How about 1.5 inches?

Assume no rock or sand for water displacement. Only thing in the tank is water.

Bunnee911 · Jan 31, 2016

Very good question. Mark the outside of the tank and measure with your refractometer. I would like to know the results.

nervousmonkey · Jan 31, 2016

Bunnee911 said:
Very good question. Mark the outside of the tank and measure with your refractometer. I would like to know the results.

There are calculators that can tell you that based on total water volume in gallons or liters, but I like Bunnees advice. Mark your tank and measure it yourself so you know for sure. Best way to be confident of the results.

TheEngineer · Jan 31, 2016

1.023 is 30.5ppt. That converts to 30.5mg/liter. A 40b is 151.4 liters (let's round that to 150). An inch of water in a 40b is 10.6 liters.

A full 40b (150liters) has 4575 mg of salt in it at 30.5ppt. If you remove 10.6 liters, your total volume is now 139.4 liters. Do the division and you wind up at 32.8 ppt or 1.025sg.

nervousmonkey · Jan 31, 2016

icecool2 said:
1.023 is 30.5ppt. That converts to 30.5mg/liter. A 40b is 151.4 liters (let's round that to 150). An inch of water in a 40b is 10.6 liters.

A full 40b (150liters) has 4575 mg of salt in it at 30.5ppt. If you remove 10.6 liters, your total volume is now 139.4 liters. Do the division and you wind up at 32.8 ppt or 1.025sg.

D***. We all just got schooled by @icecool2

Wigwam, now you have your answer

TheEngineer · Jan 31, 2016

f.lloyd.taylor said:
D***. We all just got schooled by @icecool2

Wigwam, now you have your answer

Ha! Only if I'm right and didn't mess up a conversion. :)

melev · Jan 31, 2016

Who doesn't top off their tank to avoid this happening at all? ;)

Cory · Jan 31, 2016

Need to know how many gallons 1 inch is. Plus tank dimentions.

TheEngineer · Jan 31, 2016

melev said:
Who doesn't top off their tank to avoid this happening at all? ;)

For science!! :D

Randy Holmes-Farley · Feb 2, 2016

Here's a little easier way to calculate than icecool did, but the answer will be the same (within the approximations made):

The height of a 40 breeder is about 16 inches.

So if there is 16 inches of water and you take out 1 inch (to 15 inches deep), the salinity rises by 6.7% (which means you multiply the salinity by 1.067, which is 16/15).

That would take the specific gravity from 1.0230 to 1.0245. :)

(1.067 times 23 = 24.5. )

TheEngineer · Feb 2, 2016

Randy Holmes-Farley said:
Here's a little easier way to calculate than icecool did, but the answer will be the same (within the approximations made):

The height of a 40 breeder is about 16 inches.

So if there is 16 inches of water and you take out 1 inch, the salinity rises by 6.7% (which is 16/15).

That would take the specific gravity from 1.0230 to 1.0245. :)

(The 24.5 is 1.067 times the 23. )

Well, yeah if you want to do it the easy way :P I was trying to show it in a more generalized fashion so it could be extrapolated to other tanks :)