why does my salinity keep falling from 1.026 to 1.20

[stevediaz1]

why does my salinity keep falling from 1.026 to 1.20??? this is the second time i noticed it i use a tunze osmolater 3155 ato and it tops off great but do you think its showing to much rodi i don't think so what else could cause this??? i recently started mixing my own salt water i use red sea coral pro i make sure i use rodi water and put about 1 cup of salt per gallon i bring it to 1.025 and i use a cobalt neither water heater to bring it to my tanks tempeture 78 degrees i keep my brute trash can container with my saltwater outside in the cold and heat it when i need it does that make a difference ?

 

[Lenny_S]

Do you have a protein skimmer? If you do, you have to keep track of the amount of skimmate/water it's removing and replace that volume with saltwater. If you just keep adding top off wit RO/DI water it will slowly dilute your salt.

 

[Downbeach]

What are you using to measure your SG? If its a swing arm type hydrometer, it may be giving you bad readings, and causing you to add too little salt mix when you make up your WC water, and by extension too little Ca, Mg and Alk. I would suggest you get a decent refractometer, and calibrate it with a 35ppt calibration solution, get your SG to 1.026, and revisit your tests. You'll want to make sure this is accurate before you start any dosing of those elements.

 

[Hawain_Rob]

Can u use ro water to calibrate refractometer?

 

[Downbeach]

Can u use ro water to calibrate refractometer?

You need to use a solution with the same refractive index of the sample you will be testing. Here is a good article:

http://reefkeeping.com/issues/2006-12/rhf/index.php#13

 

[TheEngineer]

Salinity only drops by removing salt. Evaporation doesn't remove salt. You would need to be removing water to do this. Like others have said, it could be your skimmer. Or you could have an error with your measurements.

 

[Piranhapat]

How long are you mixing? Before adding your new mix let it sit for awhile and test again. Make sure your using accurate Refractometers. Using RO water not right way to calibrate.

 

[Randy Holmes-Farley Verified Community Expert]

One issue may be the measurement of salinity in the cold salt water outside vs in the warm tank.

As others have asked, how are you measuring salinity?

 

[Anthony kolodziej]

This ..... if you measure in the cold your reading are off the temp should match before measuring

 

[Randy Holmes-Farley Verified Community Expert]

This ..... if you measure in the cold your reading are off the temp should match before measuring

That's true of some measurement methods and not others.

 

[Bps619]

This might not be it, but also check and see if the Tunze isn't siphoning rodi back into the sump.

 

[retiredsailor]

calibrate it with a 35ppt calibration solution

I'm not trying to hijack the thread, but how does one go about acquiring this solution?

 

[Randy Holmes-Farley Verified Community Expert]

I'm not trying to hijack the thread, but how does one go about acquiring this solution?

You can make your own if you have a scale, or you can buy it from many places under many brand names (e.g., Pinpopint 53 mS/cm calibration fluid).

Here's a recipe:

Refractometers And Salinity Measurement
http://www.reefedition.com/refractometers-salinity-measurement/

from it:

This 3.65 weight percent sodium chloride solution can be made by dissolving 3.65 grams of sodium chloride in 96.35 grams (mL) of purified freshwater. This recipe can be scaled to any appropriate size if suitable instruments are available (36.5 grams in 963.5 grams (mL) of water, 0.365 grams in 9.635 g (mL) of water, etc.).

This concentration roughly corresponds to ¼ cup (73.1 g) of Morton’s Iodized Salt dissolved into two liters (2000 g) of water (giving very slightly more than 2 L of total volume).

 

[stevediaz1]

What are you using to measure your SG? If its a swing arm type hydrometer, it may be giving you bad readings, and causing you to add too little salt mix when you make up your WC water, and by extension too little Ca, Mg and Alk. I would suggest you get a decent refractometer, and calibrate it with a 35ppt calibration solution, get your SG to 1.026, and revisit your tests. You'll want to make sure this is accurate before you start any dosing of those elements.

i use a redsea refractometer

 

[stevediaz1]

One issue may be the measurement of salinity in the cold salt water outside vs in the warm tank.

As others have asked, how are you measuring salinity?

i use a redsea refractometer

 

[stevediaz1]

Salinity only drops by removing salt. Evaporation doesn't remove salt. You would need to be removing water to do this. Like others have said, it could be your skimmer. Or you could have an error with your measurements.

your right but i only remove about 1/2 cup of skim every 4 to 5 days is that enough to lower my levels

 

[stevediaz1]

How long are you mixing? Before adding your new mix let it sit for awhile and test again. Make sure your using accurate Refractometers. Using RO water not right way to calibrate.

i mix about 1 hour then let it sit

 

[stevediaz1]

One issue may be the measurement of salinity in the cold salt water outside vs in the warm tank.

As others have asked, how are you measuring salinity?

I'm using a refractometer by redsea i use rodi water to calibrate it and when i mix my salt i mix it for about 1 hour with a heater to get it to 78 degrees but takes for ever being that i keep it outside and its cold this time in california it gets down to mid 50's in the night but my tank is a 78 degrees year round i remove about 1/2 cup of skim from my protein skimmer every 3 to 4 days is that maybe the issue my alk,ca,mg are out of whack I'm waiting to dose to rectify this problem soon does this cause a problem with my salinity

 

[stevediaz1]

This might not be it, but also check and see if the Tunze isn't siphoning rodi back into the sump.

thats what i was scared of but how can i do this I'm not aware when its replacing any water back into the tank

 

[TheEngineer]

Pick up some 35 ppt calibration fluid or make it according to Randy's recipe and calibrate your refractometer. 1/2 every few days is not much unless your tank is a 3 gallon.