Hi,
As a followup to this thread, I contacted DOW regarding
the application of Great Stuff to ponds & waterfalls.
Here is the reply I received:

Mark,

The Great Stuff will work fine in your application. The surface area does
not need to be completely dry since the foam cures by absorbing moisture.
The cured foam is organic material so it will not harm the fish or plant
life in any way. If you have any further questions please let me know.
Regards,

Sean Ramballie

______________________________________

The Dow Chemical Company

1881 W. Oak Parkway

Marietta, GA. 30062

Ph. (678) 269-1262

Fx. (770) 423-4395

email:

"O3raledale" wrote in message
...
hello all,
I've been reading and learning here for a few weeks. Two weeks ago I
finally
got my small pond in (my first one) It's 4'x6' 18" deep with a 30 gallon
biofilter, bottom inlet, spilling into a 10 foot long stream that empties
back
into the pond. Well all of the water is flowing under the rocks in the
little
falls and I'm planning on using spray foam to seal the rocks so the flow
goes
over the rocks. I have about 20 little gold fish (15 one inchers and 5 two
inchers) and a bunch of pond plants already in the pond. On Sunday I was
planning on turning off the pumps and draining the stream (the filter has
a
check valve in line so it won't empty) removing the rocks and
cleaning/drying
the stream liner and reinstalling the rocks while using the spray foam.
After
I'm done with the foam and rocks and all looks good how long should I wait
before turning the pump back on? Will the not completely set up spray foam
hurt
the fish or water? Will the foam be effective sticking to the wet rocks?
Any
other thoughts and/or tips?
Thanks for any help,
Pat