I would add flow, vac your sand bed to remove as much as possible and add some phosphate media. The phosphate media will starve it out, its going to take at least a week or two, but if you keep those phosphate pads clean, they will keep your tank clean. do you have a HOB filter? canister? sump? You just need to get the filter pad in a place it will receive a lot of flow and clean out your water.You can also run it in a filter bag if you want.....heres a link to some of what im talking about. This will be your best way to erradicate quickly.
http://www.marinedepot.com/Seachem_Phos ... 55-vi.html
I would also siphon out the red/green slime directly while doing a water change, this will also help. I had red slime for months when I first set up my tank. Just have to watch nutrients in and out. :)