TSP - Trisodium Phosphate is a banned substance in some states and
you will not be able to find it for sale. This topic was discussed at
some length quite recently, and I’m sure you will find it in the
archives. An Orchid participant mentioned a few months ago that
phosphates apparently facilitate undersirable growths in public water
supplies, rivers, lakes, streams, etc. I guess that’s why many
products such as laundry detergents advertise that they are “phosphate
free”. Rio Grande & other suppliers sell Cupronil and similar
products. Make your life a little easier & buy a bottle. It’s not
worth the bother to get obsessed with making your own if the
ingredients aren’t readily available

Gail Middleton
Brooklyn, NY.