'betta Water' For Saltwater Top Up?

[fantaman]

Can one use 'Betta Water' (From Petco) as a RO/DI water source for saltwater tank top up? 
 
On the Petco website it says that this water is processed by RO and has no additives.
http/www.petco.com/product/12059/Petco-Betta-Water.aspx?CoreCat=OnSiteSearch
 
Thanks!

 

[Getthejist]

Why wouldn't you use regular R.O water? Also that betta water is unbelievably expensive.