Are you sure there's a need for it? I can't think of a good reason to go to all that effort unless the previous plant was diseased. Some people worry about about mineral accumulation in media like this, but it's not a concern when you look at it from a plant's perspective. Plants are only affected by minerals that are dissolved in the soil solution, and these minerals are easily flushed away during watering. Minerals that are adsorbed onto a medium like Prime Agra do not contribute to soil solution TDS, and therefore have no effect on roots.

I reuse all my inorganic media with no special treatment.

I agree, probably over kill. I reuse my rocks after washing. If you want to continue the clorox wash and sun-dry steps, that will kill algae and any insects. Properly watered orchids don't have mineral buildup problems for most water sources.

I soak mine in 10% bleach solution over night, rinse thoroughly, soak over night again in plain water, then air dry it to make sure the chorine has been removed.

I clean mine because of the possibility of virus not because of a mineral build up.

Brooke

Thanks for the input.
I was most concerned about algae and virus, being that I'm sure I must have some among 200 plants even if it is not clearly evident.
Wasn't sure about the second step. I am an over-waterer, so guess I don't have to worry about the minerals.
Have already done the chlorine soak, rinse, and dry; so guess it is on to repotting!
Jan

Ditto, I soak in Chlorine only.

Nick