Does it matter what kind of water is used in humidity tray?

[BonsaiQueen]

Hubby and I have switched over to rain water for our delonix and for my Fukien for watering purposes - and they love it! I have also been using rain water in the humidity tray for my Fukien. Is this necessary or will tap water do? Will salt buildup be an issue with using tap water in humidity tray? It sounds like a silly question for me to ask, but I really don’t know the answer. If we could save rainwater for watering purposes that would be great, but if I need to continue using it in humidity tray, I will do so too.

Thank you!!

 

[Bonsai Nut]

Generally speaking, the idea of humidity tray is to create a "zone" of humid air around your tree. Because you are dealing with water vapor, it doesn't matter what water you use, because any minerals or salts will remain in the tray as the water evaporates. However... I am of the opinion that humidity trays don't really work, unless you are somehow enclosing the area to keep the water vapor in.

 

[penumbra]

Humidity trays make a world of difference for me, but I do use large deep trays. I have 8 or 9 re blooming orchids in one tray and 3 indoor bonsai in another at this time. My trays are about 24 x 18 inches and 2 inches deep with fine aquarium gravel. I use well water which is very hard and causes minor calcium build up which I flush out 2 to 3 times a years.
I would not have much faith in small shallow trays unless you add water at least one a day and even then I am not sure.

 

[Wires_Guy_wires]

Tap water will over time cause salts to build up. Flush it a few times with rainwater every month to limit that effect.

 

[BonsaiQueen]

Generally speaking, the idea of humidity tray is to create a "zone" of humid air around your tree. Because you are dealing with water vapor, it doesn't matter what water you use, because any minerals or salts will remain in the tray as the water evaporates. However... I am of the opinion that humidity trays don't really work, unless you are somehow enclosing the area to keep the water vapor in.

Thank you!! We will do a lot of research on a nice enclosure that we could make for them for he time that they are indoors! Thanks for sharing and the nice tip! ?

 

[BonsaiQueen]

Humidity trays make a world of difference for me, but I do use large deep trays. I have 8 or 9 re blooming orchids in one tray and 3 indoor bonsai in another at this time. My trays are about 24 x 18 inches and 2 inches deep with fine aquarium gravel. I use well water which is very hard and causes minor calcium build up which I flush out 2 to 3 times a years.
I would not have much faith in small shallow trays unless you add water at least one a day and even then I am not sure.

After reading what @Bonsai Nut shared about needing an enclosure, I can see how the deeper trays can be better than the shallow trays. Thanks for sharing your experience! ?

 

[BonsaiQueen]

Tap water will over time cause salts to build up. Flush it a few times with rainwater every month to limit that effect.

Thank you, will do!!

 

[Wires_Guy_wires]

I also did some measurements on a wind free day.
There's a reason why the tree roots grow through the pot holes; it's damp enough.
But just for the first inch, after that the ambient air takes over.

Just like how a lit bunsen burner creates an umbrella, trays create a localized micro-dome of humid/saturated air. But a little airflow can ruin that effect for both the burner as well as the tray.
Check your lawn on a cold day, if it's misty outside, you'll see that there's a foot tall layer of somewhat stale air. It works in the same fashion when scaled down.