Constructing A Concrete Pond

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F.Y.I. BEFORE YOU CONSIDER BUILDING A CONCRETE POND YOU WILL HAVE TO HAVE BASIC MASONRY KNOWLEDGE. IF THIS IS NOT YOU, GO WITH A LINER!

THAT SAID:

Excavating a concrete pond is done along the same lines as for liner ponds, except that some allowances need to be made for a base about 6″ thick and sloping sides 4″ . If the sides will be vertical allow for 6″ walls like the base. The depth of the excavation should include a layer of compacted hardcore like crushed stones or bricks.

STEP 1:

Cover the base of the excavation with hardcore as described above. Compact it into a layer that is 6″ thick. Renting a electric tamper may be a good idea if your soil is sandy.

STEP 2:

Make up a dry mixture of concrete consisting of 3 parts coarse aggregate; 2 parts sharp sand; 1 part cement. Mix thoroughly.

STEP 3:

Add enough water to form a consistency that allows a slit made with a shovel head to remain open.

STEP 4:

If the pond is small combine steps 5 and 7 into a single operation. If your pond is fairly large then follow steps 5, 6 and 7 separately.

STEP 5:

INFORMAL PONDS:

Lay concrete along base and around the sides of the pond to a depth of about 2 1/2

FORMAL PONDS:

Lay concrete only along the base of the pond to a depth of about 2 1/2

STEP 6:

INFORMAL PONDS:

Cover base and sides with a layer of heavy gauge chicken wire to prove reinforcement. Steel mesh or rods may be used if the pond is very large.

FORMAL PONDS:

Use chicken wire only on the base, with rods or mesh being installed later when the pond sides are constructed.

NOTE: Either way, bed the chicken wire into the concrete to ensure no exposed areas protrude after Step 7 is done. Exposed Bits of wire will rust quickly and cause problems later on.

STEP 7:

INFORMAL PONDS:

Lay the remaining concrete to a depth of about 5 1/2″ along the base and 3″ on the sloping sides and shelves.

FORMAL PONDS:

Finish laying the base to a depth of about 5″ but only if shuttering, can be installed immediately. Otherwise, do not complete the base but’ key the surface instead to ensure an effective joining when the final layer of concrete is added on. (Shuttering are the wooden forms you need to hold the concrete in place for it to dry and harden.)

HINTS:

The shuttering or forms should leave at least a 6″ gap between it and the earth wall.

Slowly pour the concrete and insert chicken wire or other suitable reinforcement material.

STEP 8:

FORMAL PONDS ONLY:

Install shuttering/forms if the pond is small enough to allow this to be done without having to step on wet concrete.

STEP 9:

FORMAL PONDS ONLY:

Mix up concrete of the same grade and consistency as that used for the pond bottom base and shovel this into the cavity between the form and excavation walls. Always wet the shuttering or forms with soapy water before you start. You don’t want it to stick to the forms. Once you have poured a layer a few inches thick, you can place reinforcement rods or wire down in the concrete supporting it at the top of your forms.

STEP 10:

FORMAL PONDS ONLY:

All the sides to set for 24 hours. Then remove shuttering/forms.

STEP 11:

FORMAL PONDS ONLY:

Finish laying pond base if it was not completed at the end of step 7. The final thickness should be around 5″ total. Allow to dry 24 hours.

STEP 12:

FORMAL AND INFORMAL PONDS:

Prepare a dry mixture consisting of 3 parts sharp sand; 1 part cement, add waterproofing powder at this stage, if you want. If you are wanting to add concrete dye for coloring, this is the time to do it!

STEP 13:

Gently add water to the dry mixture until it is like a stiff paste. Be sure to prepare enough to cover the whole pond to a thickness of 1″ . This is called rendering. Apply the rendering with a trowel leaving no ridges or depressions. Get it a smooth as you can. Work quickly so it doesn’t dry out.

STEP 14:

You may find that a small amount of water collects in the bottom. If so, it will disappear is an hour or so. If it is hot outside, you should cover the surface with most sacking to slow down the drying process.

NOTES: Opinions vary as to how long you should wait before filling with water. If your weather is damp, allow it to cure for 1 week. If the weather is hot or really dry, 3 days should be sufficient.

MAKING THE POND SAFE FOR AQUATIC LIFE:

A newly constructed pond is far to hostile to all forms of life, so you must make it safe for the fish and plants. The main danger is from the lime in the concrete. We recommend building one in the fall allowing for the winter months to achieve a safe level of maturity.

You can seal your new pond by applying 3 coats of polyurethane resin to the surface. This coating dries in about 30-45 minutes, allowing you to complete your sealing sooner than other products. BE SURE that you completely cover the surface leaving NO holes or untouched areas. If you do, the lime will leech and you will kill everything in your new pond.

IMPORTANT POINT: You must fill and drain the pond several times before filling to introduce fish and plants. This removes impurities and render it safe. Last wash should be make with a mild detergent and a good rincing. If you want wait a few months and fill and drain the pond 2 times a week for 2 months you can eliminate the above procedure, but don’t know why you would want to.

Well, that’s it! Now you have the info you need to build a really nice Formal or Informal concrete pond. One last point here. Concrete does deteriorate over time if left unattended. Cracks appear and leaks develop. Some people opt for installing a EPDM liner over the new concrete which means your pond is ready to go as soon as you fill it. No waiting!