Salt mix

[Signalhead]

Good morning, I have a question about math and salt mixing, math does not lie . I use Instant Ocean Mix. A box that makes 200 gallons of salt water, 4 plastic bags Should be 50 gallons x 4 bags= 200 gallons. I get salinity of 1.021 per 50 gallons.

If I buy the individual bags to make 50 gallons. Same salt. I get salinity of 1.025-
0 TDS, temp at 78°, mixed for about 3 hours, mixed on the same day of the week. What I'm doing wrong.
Thank you.

 

[JayM]

How much does each bag weigh?

 

[Signalhead]

How much does each bag weigh?

15 lbs. Per their site

 

[Shibaken3]

https://www.instantocean.com/products/sea-salt-mixes/sea-salt
its suppose to mix at 1.022

 

[Signalhead]

https://www.instantocean.com/products/sea-salt-mixes/sea-salt
its suppose to mix at 1.022

I use the orange bag. Is weird

Thank you!

 

[Randy Holmes-Farley Verified Community Expert]

I don't know how accurate that 15 pounds is, but they also say:

NOTE: 1.4 lbs of Reef Crystals is formulated to create 5 gallons of saltwater at a specific gravity of 1.021.

That rate is 1.4 gallons per 5 gallons = 0.28 pounds per gallon.

Thus, 4 bags = 60 pounds. Put into 200 total gallons, that makes 0.30 pounds per gallon, so should make a sg of about 1.0225 (calculated from the 0.28 pounds/gallon gives 1.021)

That is very close to what you get, given the variability of home measurement of specific gravity.

The remaining question is what you seem to get a higher value using the single bags.

How are you measuring specific gravity?

 

[Signalhead]

I do a 50 gallons water change. So the box salt is what I get 1.021. The single bag mark for resale is get the 1.024. I use a reflectometer (is calibrated) and a digital (ice cap just want to know the why? Is same product just a different bag.

 

[Randy Holmes-Farley Verified Community Expert]

I do a 50 gallons water change. So the box salt is what I get 1.021. The single bag mark for resale is get the 1.024. I use a reflectometer (is calibrated) and a digital (ice cap just want to know the why? Is same product just a different bag.

I understand. Instead of speculating why there may be different amounts of salt in the bag, which is possible in any single case but unlikely to be generally true, I was pursuing an extremely common issue with salinity measurement: inaccuracy and variability. It's far more common than reefers want to think.

How do you calibrate your refractometer?

Same for the ice cap.

 

[Signalhead]

With the solution from the store. Different ones too. This a long term issue. I was using the box type and one time Amazon had a sale on the bag, so I order one. Noticed the difference try the bag few times. With the same result. Salt is been stored inside the house with AC running.

 

[Randy Holmes-Farley Verified Community Expert]

With the solution from the store. Different ones too. This a long term issue. I was using the box type and one time Amazon had a sale on the bag, so I order one. Noticed the difference try the bag few times. With the same result. Salt is been stored inside the house with AC running.

Nothing can happen to a salt mix bag to impact the final salinity in the way you note. There cannot be an explanation aside from variable total salt in each bag, or salinity measurement issues. i urge you to not ignore salinity measurement as an issue, but regardless, just make up any of them to your target using a properly calibrated device.

proper calibration may NOT be as per manufacturer recommendations, depending on the device used. refractometers in particular often come with advice suitable for materials other than seawater, but do not clearly say that.

 

[Signalhead]

I checked the weight on a separate bag from a 200 gallon box and a 15 lb bag (individual bag) and there is one and 1/4 lbs. Difference.

 

[Signalhead]

I checked the weight on a separate bag from a 200 gallon box and a 15 lb bag (individual bag) and there is one and 1/4 lbs. Difference.

 

[Randy Holmes-Farley Verified Community Expert]

Thanks for the update. :)