I mixed a 5 gal bucket of fresh RO/DI according to the IO instructions (1/2 cup per gallon) which according to the bag should have given a level of 1.026. I tried a refractometer, one of the floating thermometer/salinity measuring devices and my apex salinity probe and the highest it measured was 1.02 (with the floating device). The refractometer showed just under 1.02 and the apex shows 1.019
I'd rather not go into the store right now (no one in our area is taking social distancing seriously). It was a small bag so I'm fine just eating the cost for now but definitely need to get a fresh bag of something.
Does the bag really say 1.026 is what you get from that specific mixing? 1.026 isn't even in their recommended range (useless as it is).
The web site seems to suggest it will be lower:
Shop Instant Ocean for only the best aquarium sea salt mixture for your marine tank!
www.instantocean.com
1. Mix Instant Ocean® with ordinary dechlorinated tap or purified water.
NOTE: To prepare small quantities, use 1/2 cup of Instant Ocean per each U.S. gallon of water. Mix as directed.
2. Stir vigorously to ensure a good mix. Although the Instant Ocean solution may be used immediately, we suggest aerating the water until it achieves oxygen/carbon dioxide equilibrium.
3. Measure specific gravity with an Instant Ocean® Hydrometer.
Recommended Specific Gravity Range: 1.020 - 1.024 at 77°F.
NOTE: 1.5 lbs of Instant Ocean is formulated to create 5 gallons of saltwater at a specific gravity of 1.022.
4. Adjust salt level accordingly. If specific gravity is too low, add more Instant Ocean. lf too high, add more dechlorinated water.
5. Change 20% of aquarium water every two weeks to maintain optimum water quality.