Reef Chemistry Question of the Day #252 Raising Salinity

[Randy Holmes-Farley]

Reef Chemistry Question of the Day #252

Suppose that you discover that, due to a calibration error, the specific gravity of your reef aquarium water is only 1.021.

You want to raise it slowly and gently by replacing evaporated water with new salt water that has a specific gravity of 1.026.

Since you know that you evaporate 1.5% of the total water volume each day, you predict that in 11 days the specific gravity will be where you want it. That is, at the end of 11 full days of evaporation and salt water replacement, you will be at your target.

What must have been your specific gravity target for this solution to work out?

A. 1.0232
B. 1.0241
C. 1.0249
D. 1.0253
E. 1.0264

Good luck!

































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[Shon]

So, a 100g tank @ 1.021 loses 1.5g a day, replaced daily with 1.5g new saltwater. The salinity of the 100g, when at loss of 1.5g raises the salinity to 1.0214. Adding in the 1.5g of 1.026 brings the tank to...

wait there is a calculator for this.. sort of..

https://www.hamzasreef.com/Contents/Calculators/SaltwaterTopOff.php

enter value;
100gallons
1.021
(answers)
1.5x11=16.5g top off
top off salinity (target 1.026)

after trying answers..

D worked


but I still want to know the daily swings!
So add 1.5g of 1.026, to 98.5g of 1.0214.. makes 100g of ???

Edit: I think D might be wrong.. using a different calculator lead me to 1.0218 by the 11th change.. which is not an answer.

 

[Randy Holmes-Farley]

Edit: I think D might be wrong.. using a different calculator lead me to 1.0218 by the 11th change.. which is not an answer.

That one probably assume a 1.5% water change, not evaporation replacement.

 

[MnFish1]

That one probably assume a 1.5% water change, not evaporation replacement.

Yes - thats what that one is lol I got the same one