water top off

[EvanStorzuk]

i have a 40 gallon tank so it evaporates about 1/2 a gallon a day. i can see the water level go down through out the day. but every time i check the salinity it stays the exact same. when i top of with rodi water, some times salinity even drops. this doesnt make any sense. does some one have an explanation?

 

[Nano_Man]

No small leak in tank sump equipment. If evaporation is happening your salinity goes up and you top off you are diluting your salt water back to the correct salinity . Have you got a mark on the tank for topping back up to the correct salinity. What are u using for measuring salinity

 

[gbroadbridge]

i have a 40 gallon tank so it evaporates about 1/2 a gallon a day. i can see the water level go down through out the day. but every time i check the salinity it stays the exact same. when i top of with rodi water, some times salinity even drops. this doesnt make any sense. does some one have an explanation?

You're probably not going to be able measure a 1% salinity drop.
If you measure salinity after you add water perhaps the water has not mixed yet.

What instrument are you using to measure salinity?

 

[EvanStorzuk]

You're probably not going to be able measure a 1% salinity drop.
If you measure salinity after you add water perhaps the water has not mixed yet.

What instrument are you using to measure salinity?

i am using a refrac and i do have a mark to add. no leaks any where

 

[gbroadbridge]

i am using a refrac and i do have a mark to add. no leaks any where

Well, I honestly would not worry about it - that change in salinity is not measurable using a hobby level device, and nothing in the tank will notice.

 

[Randy Holmes-Farley Verified Community Expert]

I agree. Note that the expected change when evaporating 1% of the tank volume is from sg = 1.02600 to 1.02626. No hobby refractometer can detect that difference.