Fluval Sea salt

[Aquattro]

Not sure where you're buying salt, but the fluval here is almost double IO. And using IO, I add 25g of Ca to my 50g new water, which costs me about $18 for a year and a half of Ca.
Honestly, if IO is working, leave it alone. The fish store is pushing fluval due to pressure from the sales rep. And probably higher profits.