Can you use tablet or granular salt in a Harveys HV3 water softener?

rachelmiller79

I am about to have a Harveys HV3 water softener installed. All the literature provided and online states that block salt is required, but I have also read that you can use tablet salt (by companies who sell water softener salt)

On Harvey's website they push the point that block salt is lighter and less bulky, but in their FAQs, they specifically say this:

Our water softener is designed for block salt. We wouldn’t recommend using granular or tablet salt as it can block the tray and cause problems with the brine valve etc

Is this actually true, or a load of nonsense just to push their own block salt sales? I notice that they state that if you don't use block salt or salt of a lesser quality then the warranty is not valid.

Thanks!