FG,

A single mosquito dunk can treat several gallons of water, although it takes it a while to "break down" and disperse. The mixture ratio is not at all critical.

I usually break a dunk up into several pieces before using it. I have found them to be very effective at both preventing fungus gnats and getting rid of them after they occur.

The BT in the dunks kills the tiny fungus gnat maggots, but apparently does not kill the flying adults. The fungus gnat life cycle is very accelerated, so you should get reasonably prompt results after you start using the Mosquito Dunks.

MM

How much of one of those "dunks" to use depends on your plant or pot size. For a small pot only a little of the Bacillus thurigiensis - Israelensis is needed while a larger pot may need close to one whole dunk. Fungus Gnats develop when soils are kept too damp, so in addition to using the BTI dunks watch how often and how much you water. Less often but more water is better than a little water frequently.

Thanks for such quick responses, kimmsr and maineman...I will start diluting my mosquito dunk and applying your suggestions today. I appreciate your help, it's exciting to have a new "plant memeber" of the household, but sad when I can't figure out how to help it.
If either of you are familiar with Gardenia plants, I posted a question in the 'houseplant' section yesterday, as well! thaks

You can make it easy on yourself and just float a dunk in your container of any size overnight. Then save it to use again or pass on to a friend with a water feature in their garden - intermittent wetting and drying of the dunk does not alter it's effectiveness according to the package directions.

I break the dunks into quarters and put a piece into a gallon container. I let it soak overnight and use the water the next day. I reuse the same dunk for quite a while. Since the fungus gnats thrive in moist soil I'll water the plant thoroughly with the bt once then I put it in a spray bottle. I spritz the surface of the soil every couple days, just enough to penetrate the top couple inches. It seems to work and keeps the roots from staying wet. I use sticky paper for the adult gnats.

Karyn

I have a question regarding watering and mosquito dunks. I've got a piece of dunk floating in my rainbarrel -- it's okay to water my veggies with that water, isn't it? And is it unhealthy for birds to drink water with that in it?
I put another piece in my fountain, and the birds love the fountain.
Thanks,
Amelie

thanks for your responses. I did break up a dunk and dropped the pieces into a gallon of water to sit overnight. I watered the schefflera the next day after I repotted it in a new pot with new soil...and so far no fungus gnats are visible. Actually, some of the pieces of the dunk which broke up are sitting on the top layer of soil from the watering, so I don;t know if that's helping, but there are no visible signs of those pesky flying gnats, and the plant seems to have perked up!

Sorry, Amelie, I don't know the answer to your question...

As far as I know the dunks aren't dangerous for any vertebrates.
Karyn

Amelie-
I found my package of mosquito dunks (BT), and on the back of the package, it states that it's ok to use them in places such as: animal watering troughs, bird baths, flower pots, rain barrels, gutters, etc. so it seems ok to continue using them in your bird bath!

BT is deadly to certain insects, no harm to birds,mammals, etc