I have been following Rays S/H system as close as I can and the orchids are growing well but I am getting this slimy black substance on the medium and the roots.
Are you sure it is not a dark green algae? I get algae growing on my LECA when the pot is getting plenty of light, but it doesn't seem to bother the plants. If it's really roots turning black, that sounds bad--fungal I would guess.
Hi Fishmom. Thanks for that. I have been mixing "alginox" a pool algaecide with my fertilizer but not doing much. When I said black, the roots above the Leca are a very dark green and slimy and the Leca is black. My shade cloth has been 70% so I put an extra 50% over this summer. If you say it wont hurt the plants I'm happy.
If it's really algae, flushing to overflowing might float some of the stuff out and you can see better what it is. I'm guessing Ray will chime in with better information.
I did talk to Ray earlier and he suggested I go to the forum and ask around. I havn't done this before so it is a new experience for me. I appreciate your help as there are very few S/H growers here in Australia so it is hard to exchange views.