Unopened, reef salt can last for a very long time. This is good news for bulk buyers who favor the most cost-effective solutions for buying many months or years’ worth at a time.
The only thing to keep in mind is that sometimes moisture can get into your reef salt.
Whilst this will not make it ‘bad’ per se, it may well cause clumps and lumps to develop in the reef salt mix.
As long as it is stored in an airtight container, you can rest assured that the reef salt is likely to be fine for a long time.
That being said, we always recommend checking with the individual retailer or on the information included to be safe.
This is because all reef salts are made slightly differently, and so they may well have different shelf lives.