water salt salinity spike?

webbrage · Apr 12, 2016

SO i setup a 65 gallon with a 25 gallon sump, fill the tank with saltwater from the store go back next day and test it the test said it was .028 so he said i should bring it down to .026 so i dump 4 gallon and put 4 gallons of RO. go back 2 days later and its up to .038 -035 in that area i know water will evaporate and salt can go up but dang how is this possible to jump that high. Today i went and got it tested was still up there and now we got it down to .029 I'm going to go tomorrow to test it again and hopefully have it where i need it. but today i also went ahead and got 15 gallons of RO for top off so daily i will maintain it right on point

TheEngineer · Apr 12, 2016

Are you using a hydrometer or refractometer to test?

webbrage · Apr 12, 2016

local store is using a refractometer
he used the tank water they have and it was right on

webbrage · Apr 12, 2016

and he checked the RO water
and saltwater everything is correct somehow mine spiked to hell

TheEngineer · Apr 12, 2016

webbrage said:
local store is using a refractometer
he used the tank water they have and it was right on

Assuming their refractometer is calibrated properly, salt levels go up in one of two ways generally: evaporation and adding salt. In rough numbers 1.038 is 50ppt and 1.028 is 37 ppt. That's a change of 13g per liter.

Your system is 340liters, so that would mean an extra 9.75 pounds of salt were added to your system. Replacing 4 gallons would from 1.028 water would remove 1/3 pounds

Long story short, something doesn't add up.

jsker · Apr 12, 2016

What temp is the water? The warmer the water the high salinity. Could it be that the heater has gone bad? and by the time your get to the LFS the water has cooled down a bit? The reason why I am asking is that I moved my Apex and was setting up the outlet again with my heater and my temp was way high 81.7 and my salinity 35.8/1.027 I now have the setting right at 78.3 and my salinity is 32.8/1.0247. I did not add water or salt. I was the heat send the salinity high.

TheEngineer · Apr 12, 2016

A handy article by @Randy Holmes-Farley is readily available, of course!
http://www.advancedaquarist.com/2002/1/chemistry

TheEngineer · Apr 12, 2016

If the refractometer was calibrated at 77 and the tank is at 85, the reading would be lower than the actual salinity. I think... It's late and I don't want to math anymore.

sbash · Apr 12, 2016

How new is the tank, and how did you mix the salt exactly? If you mixed the salt in the tank (without adequate water movement) some salt could have settled, which has now dislodged and dissolved (which would account for the second part of IC2's statement), thus raising the salinity. Getting your own refractometer is well worth the cost, if you shop around, you can find them as low as 25-30$. Using other peoples calibration tools can lead to varied results (for example, was it the same refractometer from the store, and was it calibrated from the same calibration fluid???). In my 65 (no sump) it would probably take two week or more for the evaporation to raise the salinity that much... ...Very odd indeed...

TheEngineer · Apr 12, 2016

Thats a good point @sbash. Could be salt that was in there but not dissolved.

webbrage · Apr 12, 2016

sbash said:
How new is the tank, and how did you mix the salt exactly? If you mixed the salt in the tank (without adequate water movement) some salt could have settled, which has now dislodged and dissolved (which would account for the second part of IC2's statement), thus raising the salinity. Getting your own refractometer is well worth the cost, if you shop around, you can find them as low as 25-30$. Using other peoples calibration tools can lead to varied results (for example, was it the same refractometer from the store, and was it calibrated from the same calibration fluid???). In my 65 (no sump) it would probably take two week or more for the evaporation to raise the salinity that much... ...Very odd indeed...

store bought natural salt water

webbrage · Apr 12, 2016

jsker said:
What temp is the water? The warmer the water the high salinity. Could it be that the heater has gone bad? and by the time your get to the LFS the water has cooled down a bit? The reason why I am asking is that I moved my Apex and was setting up the outlet again with my heater and my temp was way high 81.7 and my salinity 35.8/1.027 I now have the setting right at 78.3 and my salinity is 32.8/1.0247. I did not add water or salt. I was the heat send the salinity high.

no heater is in the tank its at a constant 78-80