Thank you all for the replies.. and yes Dick, I have not posted for a while, used to do a bit in NI but work has been rather busy (which is good, more money to pay for this hobby)
My main water is considerably soft (averages on kH of about 40ppm and gH of about the same) but I just find my showa is not getting the black as nicely as I'd like and I am talking about a line of showa that I have been waiting for 4 years (I think that's the limit of my patience). I also notice putting the same line (its sibling) on another pond (in the beaches area) brings out the sumi nicely.. well reading the contents of Refresh is has silica ??, hence the reason I am keen in trying the product