Wendyb,

I suggest you take a look at Physan 20.

MM

The white dust could also be deposits from the mineral content of the water.

I'd say to strip it all down regularly, say like 2-4 times a year according to how much it needs it, and just thoroughly clean everything.

Definitely do a 10% bleach solution to kill whatever crud might want to grow in there. I'm not sure on the rocks what would bring back the shine the best. You might need to CLR them or something like that.

Just make sure you thoroughly rinse everything afterwards. Rinse it till you're sure it's clean, then rinse some more. (Let it soak in a big bucket or something overnight, then rinse again.)

Once everything is nice and new looking again, just clean it whenever the luster seems to be dulling and it shouldn't be hard. Just a couple hours soak in bleach water, a few hours in clean water, and you're done.

Thanks for the ideas. mineral deposits is possible. I hadn't thought of that. It did kinda look like the white layer that clay pots get. I clean those pots in a vinegar solution with some bleach for good measure.

Until I get a chance to dissassemble and clean well, I haven't been filling the trays with water. I've just been misting the plants more often.

I was thinking that after they are washed and dried, applying a spray of polyurethene to bring the shine back. That could be what was on there in the first place. If so, makes sense that it would wear off.

-Wendy

If I interpret correctly, you have stagnant water. I don't recommend stagnant water. Drain off and discard runoff water, automatically by gravity.

Let me know how it goes, Wendy. If you have any problems or run into any hitches I'll be happy to lend my brain for what it's worth.

lermer makes a good point on the stagnant water - it's always best to avoid it but if you haven't had a major problem so far I'd have to guess it's not likely to cause you one.

I don't understand the stagnant water point... what about:

for humidity grow on a pebble tray with water

isn't that always going to be stagnant water?

Stagnant water reminds me of mosquito larvae opportunities outdoors.

this is a 4' x 1' long 1" high tray covered with pebbles and plants and with cords and lights on its underside. tipping it to discard runoff water is not an option.

Stagnant water causes a number of different problems, but the point I was trying to make earlier is that if you haven't had any obvious problems so far you probably don't have much to worry about. Just keep an eye on it.

Stagnant water can attract insects (mosquitoes, various flies, and so on) as well as be a great environment for various molds, fungi, and bacteria. Those tend to be the biggest problem in hydroponics, but can also be really annoying anywhere else. A common by-product is a lot of stink and/or allergy problems.

An easy fix is to just add some hydrogen peroxide to the water whenever there's a problem, or even as a preventative. (Same reason hydroponics systems aerate the water - oxygen is bad for the bad stuff.) It breaks down harmlessly into oxygen (the bubbles) and water, and helps keep the water from looking inviting to the nasty things that want to grow in it.

Is the hydrogen peroxide bad for plants if added to pebble tray under plants. I have same problem. My prayer plant is in a clay pot and over the past month I’ve switched to only distilled water. I don’t even let the water stay but if I pick up the pot at the spot where the drainage hole is, there’s white fuzz. I wash it with windex and dishwashing liquid. I want to increase the humidity but I also don’t want to hurt the plant in the process. Do you recommend a humidifier? Thanks. Josephine