Spider Mites or Mold?

[scy]

I just bought a dendrobium. I unpotted to check the roots and potted it back up after noticing that the roots were in good condition. I used leca and added a mosquito dunk (still have a few fungus gnats left). The next day I noticed some white fuzz or webbing on the top layer of the bark mix and on the bottom of the pot. I rinsed it thoroughly under the sink and haven't seen any more webbing on the top layer of the medium. However, the bottom of the pot keeps appearing. I thought it might be spider mites, so I sprayed the bottom with malathion but it came back the next day. Is this fuzzy mold or spider mites?

I have a cymbidium infested in mites (no webbing) and scale and plan on doing a systemic dunk later today. If these are spider mites on the dendrobium, can I dunk the entire plant in the systemic or best to do the medium and then spray the leaves and cane individually?

If it's mold, should I just soak the whole thing in physan 20 solution (1 tsp per gallon dilution)?

Thanks for your help!