Building concrete ponds is not easy for anybody, and is certainly not going to be an easy task especially if you have had no or near zero experience using concrete.
When using concrete you need to not only get a good consistent mix but also the right mix as well as laying and applying it correctly. If you have had no experience then I would personally get some help from someone that has!
Some people love concrete ponds -they pre date all the modern methods and are a great attention grabber. I believe concrete ponds are best used when creating a natural shallow pond.
Dangers when using concrete
Hair line fractures
Over time concrete ponds are known to develop hair line cracks which can be almost impossible to locate. This means you have the problem of draining the whole pond and resealing it. When you have a large stock of fish this can cause problems as you will need to find them a temporary home.
Some people use a liner above or below the concrete to make sure it is completely leak free. When using a liner on top it can take away the effect you are trying to create by having a concrete pond.
Lime and toxic chemicals
Concrete consists of many toxic chemicals and lime which can make the pond water unsafe for your fish. To prevent this you can either……
Fill the pond with water and leave it to draw all the chemicals out and then empty and refill. You will need to do this 2 or 3 time to ensure that all the toxic chemicals are gone or…..
Use a pond sealant paint, this will seal the concrete and keep all the chemicals in. I personally would do both.
To be sure your pond is safe use a pH test kit to test your water. This way you will be sure it is safe before you stock any fish.
Materials you need when building concrete ponds.
Concrete 1 part cement, 2 parts sand, 4 parts gravel + waterproofing compound Mortar 1 part cement, 2 parts sand Wire mesh Most people use good old chicken wire Sealant and pond paint pH test kit
Building Concrete Ponds
There are a few methods you can use when building concrete ponds. Just remember I didn’t say it would be easy!
For a natural looking shallow pond start by digging out the area you have decided to sit your pond on. Once this is done place chicken wire into your pond covering all sides.
Next pour concrete into your pond until it builds up and all the chicken wire is covered. Use a float to give the concrete a clean smooth finish. This will also prevent fish getting injuries from any jagged edges. Cover with plastic sheeting and allow it to dry.
If you are planning a square concrete pond or intend to keep Koi that need more space, dig out your pond making sure the bottom is flat and level. Again line the bottom of the pond with chicken wire and fill with concrete until it is covering this.
Have the concrete base at least 15cm deep, more if your pond is going to be large. Tamp down to release any air bubbles and give a clean smooth finish. Once this is dry you can move on to creating the sides of your pond.
Next you need to build a box out of wood, this is called shuttering.
The box needs to be 40cm shorter in length and width and built to the same height as the pond. Place the box into the centre of your pond.
This should then leave a 20cm gap all around the box where you can place chicken wire and pour the concrete into. Once down tamp down again and leave to set. When dry remove the shuttering then the base and sides of the pond are finished.
You can always render over the pond for a professional finish. This also prevents the fish from damaging themselves, especially through mateing season as they are unable to order a king size bed like you and me.
Finally finish with the pond edging of your choice using slabs, wood, stone or what ever you fancy. Use mortar to hold the edging in place.
Then you need to make the pond safe from toxic chemicals and seal it well.
Also see koi pond construction which has a simple diagram that you can follow.
Always test your pond water before introducing any fish into a new home that you have created.
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