pebble tray maintenance re mold
I grow houseplants on a etagere setup with flourescent lights and metal trays less than 1" deep with pebbles that are just barely covered with water. I think the setup is nearly 2 years old. The pebbles were shiny small decorative river rock. The shine is now gone.
When I first set it up, I threw in some charcoal bits in the pebbles to help keep the water clean. Not sure if that had any affect. About 6 months or so ago, I noticed some dark areas on the pebbles, likely mold. I added more charcoal and sprayed with bleach and water.
Now I see a white dust-like film which I suspect is more mold.
I am wondering if there is something else I can be doing to avoid these problems?
Or just keep spraying with bleach as needed. Or cleaning them periodically (disassemble everything and rinse the trays and pebbles in bleach/water.)
I am a concerned that adding bleach to the humidity water could wick up to plants root systems or even generate foliar absorption??? I usually use pot saucers on the individual plants, but not always.