Can I use compressed coco coir for moss without letting it leech ?

Hello Everyone 👋

I would want to ask can I use compressed coco coir (coco coir cuboid) as a substrate for my moss without washing it first/letting it leech ?

I heard I need to repadedly wash it in distiled water because it contains solluble salts (specifically sodium and potassium salts) that could irritate the moss, is that true or do I not need to wash it ?

Also is coco coir alone good enough substrate for a moss ?

Thanks for your answers in advance !