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Downs By The Pond
86667 Bailey Hill Road
Eugene, OR 97405
Phone: (541)342-5887
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Pond Tips


Waterfall Basics

  1. Waterfall
  2. Support for the waterfall rocks
  3. Mortar & Spray Foam
1. Waterfall Top
The waterfall is a crucial area to get right. A waterfall with lots of splash looks and sounds pretty, but can cause significant water loss. Many times ponds that appear to have a leak are really losing water from splash-out.

2. Support for the waterfall rocks Top
If you are going to build a hill for your waterfall, remember that freshly dug soil is light and airy and will settle over time. It is important to create a support which will not settle under the weight of rocks and environmental conditions (rain). as a pile of dirt straight out of the pond will do.
Our support looks a lot like a stairway as it is formed. We use a support of 8 x 8 x16 concrete cinder blocks under the liner or platforms created from sand bags to support the weight of the rock. The soil from the excavation can then be used to backfill and cover this structure. If your soil is particularly nasty, use it up to fill the holes in the cinder blocks or a base for good planting soil.
Joining Liners
The liners should be laid like shingles, the upper liner on top. Clean the area to be joined with unleaded gas or liner primer. It will evaporate without leaving residue. Place double sided tape between the layers and roll firmly with a hand held roller to ensure adhesion. Then clean the overlapped joint. Place single face tape over the top and roll. Use lap seam caulk in a fine bead to seal the edges. We like to inspect the seam before covering with rocks.

3. Support for the waterfall rocks Top
When using mortar to seal the voids between the rocks, care should be given that the mortar does not dry too quickly, which can cause separation from the rocks and cracking. Mortar should be mixed to a consistency which will stick to vertical surfaces. Two good choices are:
Blue-Line mortar which is fast setting, enabling you to test water over the fall sooner. This mortar sets up very quickly, so only mix a small portion at a time to avoid waste.
Non-shrink grout is also a good choice. It's dry time is slower, but it has less shrinkage so there will be less separation from the rocks.
We sometimes mix the two together for optimum working conditions. Mortar and concrete will leech lime into the water raising the pH, so it is important to either leech with vinegar water or treat with Muratic Acid.
Spray foam can also be used to seal rocks in the waterfall. It is non-toxic and will not have to be sealed or leeched. This product now comes in black as well as to the standard cream color. Spray foam can be tricky to work with as it has a tendency to grow beyond the size you wish the joint to be. The cream colored variety often needs to be painted if visible since it will turn yellow with age. Also, many people have reported that after 2-3 years, it starts to degrade, and no longer holds the water in place. When working with spray foam, wear disposable gloves.
Don't forget the level! Be sure to use a level to check that the rocks are setting correctly. The rocks should be horizontally level and tilt down slightly to the front from the back for the most attractive water flow. Small stone shims can be used to keep the rocks level while they are mortared or spray foamed.

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