Disappointed with Instant Ocean salt

[Miami Dolfan]

I have a 100 gal container outside that I fill slowly with RO water a day before my water change. I always buy the 200 gal boxes of salt and use 2 bags and dump them into the bontainer where a bilge pump circulates the water for 1 hour. After I change the water, the salinity measures 1.020. why so low? I like to keep it at 1.025 and to do so, I have to add 3 bags. Just not right.

[1mbrews8]

How are u measuring salinity?

[Acroholic]

Doesn't sound right. I believe IO mixing instructions give you 1.023. For 100 gallons at 1.025 you should have to use a few cups more than 2 bags, not an entire 50 gallon bag. Have you calibrated your refractometer, or could your mixing container be a bit larger than you think?

[Miami Dolfan]

Maybe I should get a refractometer and not use the cheapy plastic Hydrometer

[grouper therapy]

If not thoroughly cleaned with ro water after each use Hydro will read lower than actual. Take it and clean it really well and then shake it to free it up and it will read much more accurate. 99% of the time hydros read off is due to improper or no cleaning of them after each use, Salt builds up over time in the swing arm pivot point and inhibits it's movement. I use to store mine in ro water.

[JennM]

IO Box makes 200 gallons at 1.020.

So the "50-gallon bag" makes somewhere between 40-45 gallons if you like it a bit stronger than that.

Jenn

[eagle9252]

I can't find it now but somewhere about 6 months ago I read that it was like 1/2 cup plus like 1 tablespoon to1gallon of ro water to make 1.026

[rdnelson99]

When I was using IO it was always right at 1/2 cup per gallon to get 1.024.

[Acroholic]

I usually mix 14 level cups to get 27 gallons at 1.025.

[Jaycen B.]

850 grams per 5 gallons will get you to 1.026. I use a digital scale to weigh my salt, SG is perfect every time.

[Miami Dolfan]

The hydrometer is new and I did rinse it with fresh water after use. I guess it read right. According to Jenn, it was right on the money.