Salt PPM question

[FreshSaltyGuy]

Sorry for the dumb question: Regarding salt Specific Gravity levels. I know mixing it we want temp between 74-76 for 1.025sg . I also understand as water temp rises so then salt SG drops correct? So at 78 degrees if my water is at 1.027-1.028 sg is that ok and I don't want to dilute it down with Rodi water to get it back to 1.025sg ?

 

[robotrash]

Sorry for the dumb question: Regarding salt Specific Gravity levels. I know mixing it we want temp between 74-76 for 1.025sg . I also understand as water temp rises so then salt SG drops correct? So at 78 degrees if my water is at 1.027-1.028 sg is that ok and I don't want to dilute it down with Rodi water to get it back to 1.025sg ?

I always thought we wanted 1.025 (35) at 78 or whatever your temp is. Am I crazy?

 

[FreshSaltyGuy]

I always thought we wanted 1.025 (35) at 78 or whatever your temp is. Am I crazy?

No I probably am lol

 

[Randy Holmes-Farley Verified Community Expert]

Let's back up and I'll make a few comments.

1. I see no reason to not maintain a typical ocean average of 35 ppt, which has a sg of 1.0264.

2. Associating a temperature with a sg is primarily an issue when using a glass hydrometer to take a measurement, not because sg itself changes much with temperature (which it does not).

Seawater density changes a lot with temp, and that is what a hydrometer measures. But sg is the ratio of the density of seawater to the density of fresh water at the same temperature, and thus sg changes little with temperature.

3. A pretty wide range of salinity seems OK, but note that all ions in the water will be lower than normal 35 ppt seawater concentration if the salinity of normal seawater is less than 35 ppt.

"So at 78 degrees if my water is at 1.027-1.028 sg is that ok "

How are you measuring that?

 

[FreshSaltyGuy]

Let's back up and I'll make a few comments.

1. I see no reason to not maintain a typical ocean average of 35 ppt, which has a sg of 1.0264.

2. Associating a temperature with a sg is primarily an issue when using a glass hydrometer to take a measurement, not because sg itself changes much with temperature (which it does not).

Seawater density changes a lot with temp, and that is what a hydrometer measures. But sg is the ratio of the density of seawater to the density of fresh water at the same temperature, and thus sg changes little with temperature.

3. A pretty wide range of salinity seems OK, but note that all ions in the water will be lower than normal 35 ppt seawater concentration if the salinity of normal seawater is less than 35 ppt.

"So at 78 degrees if my water is at 1.027-1.028 sg is that ok "

How are you measuring that?

Appreciate that info. I am using a refractometer to measure.

 

[Randy Holmes-Farley Verified Community Expert]

Appreciate that info. I am using a refractometer to measure.

Then assuming it is an ATC refractometer, you can ignore the temp part of the sg = 1.027 to 1.028 and I'd consider lowering it to 1.026 to 1.027.

 

[FreshSaltyGuy]

Then assuming it is an ATC refractometer, you can ignore the temp part of the sg = 1.027 to 1.028 and I'd consider lowering it to 1.026 to 1.027.

Ok good that's what I did I lowered it to1.026 by removing some of the salt Walter and putting in fresh RODI water. Would it be better to get to 1.024-1.025?

 

[Randy Holmes-Farley Verified Community Expert]

Ok good that's what I did I lowered it to1.026 by removing some of the salt Walter and putting in fresh RODI water. Would it be better to get to 1.024-1.025?

No, IMO that would be undesirable. you will lower important ions such as potassium.

 

[FreshSaltyGuy]

No, IMO that would be undesirable. you will lower important ions such as potassium.

Ok thanks