humidity trays developing scum or film
 

I purchased a humidity tray for some of my orchids but it seems the water that collects in the tray starts to develop a film or scum ( bacteria ? ) within a few days. I tried adding vinegar and then tried bleach but that doesn't seem to work. Maybe I'm adding too little - I'm afraid of the roots touching the water with vinegar or bleach in it. Besides replacing the water every other day + washing it is there anything I can do so I don't have to do this ? Thanx for any advice.

That is normal, that water is stagnant so...
By other hand, roots are not supposed to be in contact with the water, unless there's no option.

Mine has that when the minerals from the water build up. Try not to let the water stand for more than a day, otherwise you'll have dangerous mold and mildew take hold. I wash my trays once every other week or so to clear it of any fallen media and general "bad stuff".

You said "The water that collects". Are you letting water run from the pots into your tray when you water? That means you will get nutrients from the orchid pots, any fertilizer that you are using. That will promote algae growth in the tray.

I have water trays in my indoor greenhouse, but I don't need to wash them more often than each two weeks or so. I water my plants over a plastic basin, and add fresh water as needed to the trays, so it is not a shared water supply.

Try adding Physan 20 to the water at about 1-2 tsp/gal.

thanx for the info. it makes a great deal of sense.

---------- Post added at 07:49 PM ---------- Previous post was at 07:39 PM ----------

thanx, daveh. just got on their website + ordered it from Amazon.