Pond Fountain Info

28. What are the advantages and disadvantages of concreting in the rock?

When you say ‘concreting’, I assume you actually mean using mortar. Mortar is cement and sand like concrete but doesn’t have any gravel like concrete.

There are some obvious differences between mortaring and not mortaring the rocks in place. There is the up front cost of the mortar and extra labor. Also, mortared rock is usually much more stable than dry-stacked (mortar less) rock. The short-term and long-term effect of the mortar on the pond health is subtler. I feel the mortar plays an important role in pond health by taking up the spaces between rocks that would fill up with debris over the long haul. This debris is usually rich in nutrients that are difficult to trap in the filter where we can remove them from the system. On the other hand, mortar contains lime that raises the pH (alkalinity/acidity progression). Maintaining a balanced pH is important for water quality and algae prevention. Therefore, if mortar (or any concrete product) is used in large amounts, it may is necessary to treat the water with pH Down to maintain the proper range. As the lime leaches out over time, it will not be necessary to balance the pH to counteract the mortar. However, it may still be necessary to adjust the pH depending upon water chemistry and other factors. There is more on pH below.

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Thank you!

Jim Wilder