IO Salt
 

Got a hard time mixing IO. Always leave white residue behind. Is anybody have a same issue or just me?

sounds like you are adding it to the water to fast and it is precipitating out. i mix in a 25 gal container 4 cups at a time and never had a problem

How long between cups? I heard people can mix 25 gallons in ten minutes. Is that right?

1 cup at a time in a 5G pail and I've never had an issue. I wait till the water is clear and then add more to 1.025 and let mix over night.

I mix 37g at a time, I measure about a 4l bucket of salt and dump it in, and let it sit overnight with a heater and powerhead. Never had an issue.
I use rodi water.

I dissolve the magnesium chloride first, dump the salt and mix with 2 1400 gal powerheads. After the salt is fully dissolved, I add calcium as calcium chloride solution and keep mixing for at least 8 hours.

Are you talking loose residue or stuff that coats your mixing container? Also, how long are you waiting before use and what are you using to mix the batch? Batch size?

I generally mix close to 25 gals in a rectangular rubbermaid type container for my water changes. Have a powerhead running as I dump about 11 cups of IO into the RODI water. I don't wait, one cup after another. Once the salt is all in, I help the powerhead by using a wooden spoon to mix the salt that's collected on the bottom of the container. I'll then let the powerhead run & leave the mix for at least a day, usually two or three before the water change. Mixing container is in the relatively cool basement so a few hours before water change, I throw a couple of heaters in there to match tank temp & do a final SG check to ensure it's close if not bang on the same as the tank. Rarely add anything else like Ca or Mag, I'll dose those into the tank separately.

Been using the same container to mix for close to 3 years, so it has a good crust of residue all around. I don't sweat that, it's taken a long time to get to that state so I don't figure I'm losing that much in any particular batch that I'm mixing up. Last water change, after emptying the mixing container, I beat on it to knock some of the residue loose. Seems like mostly calcium, but just guessing there.

I'm doing the exact same thing.

No white scum?

I mix 40+ gal at a time I have a power head running and dump the salt in in about 2 min check in few hours and adjust no white scum mixes clear for me