I'm quite new at growing phals in sphag moss since I've been growing all my phals in S/H..
I am tasting those Oxygen pots and I decided to go with sphag. But lately, the top of the sphag is getting slimy green... Is this algies? Is Physan will be enough?
All my sphag grown phals. have a thin layer of green on top. It's not slimy, but I do need to watch the ventilation in that terrarium. It's no fun having your bedroom (where the terrariums are) smelling like a pond!
Essentially,spag culture & phallies do not go together; spag likes higher light & lower nutrients than phals or most other orchids. Therefore, treat the spag as a (dead) medium. Dolomite/lime will raise the pH & eliminate algae; the other approach is to block light to the moss by using a material that doesn't host moss growth. Small river pebble is a good topping, as is small expanded clay; the latter has less surface moisture & tendency to generate condensation on its surface as compared to the former, though will still host some minor algae on its porous surface.