I started out with oxalic,read msds sheets and what a pain it was,always have to watch what you doing,gloves,goggles.I switched to citric.It made my work much easier,no gloves,no protection,no health worries.Its a little more expensive,works a little slower,but fast enaugh for me.I let it dry and come back to a bright deck.I use about 8 oz per gallon of water,for a really bad deck i mix it stronger,i dont think it can hurt anything
Johny
Johny