Oncidium twinkle not thriving

[King_of_orchid_growing:)]

I've never grown this orchid in semi-hydro, but I've found this orchid to be fairly easy to grow without it.

If you're concerned about having to change out and waste organic potting materials, then growing in lava rock, and not leaving it in standing water is best.

Just water the orchid every time the media dries out.

Same with your Paph. Instead of placing it in a situation where there is a pool of standing water, try using the same LECA material and just watering it when it dries out. Like I said in your other post, Paphs generally don't like to be placed in standing water, they don't grow this way in the wild. Water usually dribbles between the crevices and keeps the Paph's roots moist. A very large majority of them are not near running or standing water.