Pond-Free 102

Chapter 5

Determining Number of Water Matrix Blocks

Let’s assume you’ll be digging a Water Matrix reservoir. One of the greatest attributes of these reservoirs is their versatility. The size, shape and depth can adapt to literally any space constraint, design or purpose – and not just for Pond-free features, but for Rainwater Harvesting as well. (In fact, a lot of reservoirs combine Pond-free or Decorative Water Features and Rainwater Harvesting together, since they are perfectly complimentary. RH reservoirs benefit from the aeration and aesthetics of recirculating water features, and the reservoir of a decorative feature is a perfect place to store and re-use rainwater. See Rainwater Harvesting for a more in-depth treatment). The versatility of these reservoirs is matched by the many ways to size and install them. You can determine the number of matrix blocks you’ll need by the space you want to fill, or by matrix block size or by gallons required, but the easiest way is simply by volume. We’ll use the Atlantic Water Gardens Eco-Blox as an example. When properly oriented, each Eco-Blox can support 7 tons (!), but only with the weight distributed evenly across the six vertical supports, so you’ll want to set them 16” wide by 17.5” tall by 27.5” long.  Each one occupies 4.3 cubic feet of space, the equivalent of 31.5 gallons (there are about 7.5 gallons in a cubic foot).

To figure out the number of matrix blocks you will need, take the cubic volume of the reservoir, divide by 4.3 and round to the next whole number. For our 12 cubic foot example, dividing by 4.3 equals 2.8, so 3 Eco-Blox will give you ample water storage once you add in the additional volume held by the Pump Vault (You didn’t forget the Pump Vault now, did you?)

Streambed Volume:
Stream L x W x .25 = cu/ft

Basin Volume (Eco-Blox)
Streambed cu/ft x 3 = cu/ft needed for basin

Eco-Blox Quantity
Basin cu/ft ~4.2 = Number of Blox