Field Manual

CWM Modular

How the system works

The CWM Modular system is made up of several hollow, airtight reservoir modules linked together. They are planted directly into the soil, typically hugging the walls of a larger container. Each system is made up of one fill module, one sensor module, and from 0-3 secondary modules. The modules are all interconnected by reinforced flexible tubing at two points, upper and lower. The lower link allows water to flow between the units, the upper link allows the vacuum created above the water level to equalize. The system is filled by hand (usually with a garden hose or similar), and closed with a stopper to make an airtight system.

The water in the reservoir flows into the soil through tiny holes at the bottom of each module. The water wicks its way up through the soil in the container until it reaches the moisture sensor, planted 1/3 to _-way down the container. The sensor tip absorbs water, and closes like a valve, preventing air from passing through the tube into the reservoir modules.

A vacuum develops above the water level, preventing more water from flowing into the soil. This vacuum is transmitted between modules by the upper connection. As the plants and flowers use the moisture and the soil starts to dry, the sensor tip dries and allows air to pass through. The vacuum is broken, allowing water to flow into the container, until the soil becomes moist again.

The process forms a cycle, interrupted only by the removal of the stopper and the filling of the reservoir. The overflow drainage adapter at the bottom allows excess water that builds up (typically rainwater) to escape without disrupting the system.

Preparation/Assembly

To confirm fit and placement, put units inside empty container. No more than 5 units should be linked together at any one time. For best results, modules need to be level within container, and of the same height. System may be directly on bottom of container, or may be supported by gravel or other fill at higher level inside container (use landscape fabric on top of gravel layer). When possible, sensor and fill modules should be separated by a secondary module. Space modules equally and determine best configuration, then measure distance between shoulders of hose bibs for tubing. Cut tubing 1" longer than measured dimension to allow for curve (see illustration). Use a shear or utility knife to cut PVC tubing.

The simplest assembly method is to connect all modules except one together with tubing outside of the planter, and set in the container. Put the final module in place, and then connect the tubing. Use hot water to soften the PVC prior to sliding it over the ridge of the hose bib (dipping the hose end in liquid soap works, too). Snap hose clamps onto tubing behind bib, and tighten with pliers. Care should be taken to make sure hose bibs don’t get plugged with soil or other debris prior to assembling hose unit.

Assemble fill pipe without cutting or welding first to determine optimal orientation and length of the straight sections. Cap is already welded to long, straight section. Place short pipe and 45° elbow into male adapter threaded into fill unit. Insert the long pipe, and orient slightly away from vertical for best filling (see illustration). Bottom of cap should extend approx. 1" above soil level. Both straight sections of pipe may be cut as needed. Using standard PVC pipe cement, weld short section and elbow into male adapter, taking care to make sure orientation is correct. Weld longer section and cap into elbow.

Installing Overflow Drainage Adapter (exterior applications)

Overflow drainage adapter may only be used with watertight, sealed planters. Adapter height may be adjusted based upon size of container, or desired excess water level. For most large containers, 3-4" adapter height should be enough. Use silicone (or equivalent) sealant to bond flat section of overflow adapter directly over each drain hole in the container. Make sure silicone adhesive is compatible with waterproofing material. Do not remove fabric from top of drainage adapter after installation. Care should be taken when planting not to bend or break adapter.

Planting the CWM Modular System

Place Bioguard fabric (small 3" yellow fabric squares) into cups of each module to prevent roots from growing into reservoirs. Begin to fill the planter, packing soil between modules and into cups. Planter Technology recommends a soil mix made of approx. 1/3 peat, 1/3 coarse organics, and 1/3 sand or perlite. Avoid the use of fine organics, and all types of field soil. Fill planter to the level of the bottom of the primary plant’s rootball. Soil must be well packed. Remove the plant from its’ plastic nursery container or wooden crate, and set into container. Fill around plant with soil, packing solidly to prevent gaps and voids.

Dip tip of sensor in water for 10-15 seconds prior to planting. The sensor should be placed approx. 1/3-1/2 down container, slightly higher if underplantings are used. In some instances this may mean the sensor is placed above the level of the CWM units. Deeper sensor placement results in lower soil moisture content, higher sensor placement results in higher soil moisture content. Pack soil as necessary to level of underplantings, making sure soil is packed as firmly as possible. Install underplantings, and pack soil between them. Top water underplantings to hydrate.

Filling and Maintenance of the System

Prior to filling reservoir, check to insure that soil is well packed, and that soil does not appear wet. Release tamper resistant stopper by turning the hex nut with a 5/16" hex wrench counterclockwise three turns. Remove stopper, fill reservoir with clean water until water fills up pipe. For easiest filling, push garden hose adapter or garden hose deep into the pipe, then start water. Having a means of stopping the water at point of filling prevents messy spillovers. Remember, if fill pipe is not oriented away from vertical, air leaving the system may cause water to back up. Once filling is complete, replace stopper, tightening hex nut with three clockwise turns to secure. Top water underplantings lightly during first week or two to encourage roots to grow into moisture zone.

If installed with overflow drainage adapter, the system may weep a small amount of water into the saucer for the first 12-24 hours after filling. Afterwards it will weep between fillings if excess water builds up after a rain, after heavy top watering, etc. Because removing the stopper breaks the internal vacuum and disrupts the system, remove stopper to check water level no more frequently than necessary -typically every week to three weeks (more frequently in extreme conditions). Fertilize with Planter Technology HM-10 time-release fertilizer for sub-irrigation systems, or other water-soluble fertilizer. When using other fertilizers, use _ the strength recommended by manufacturer.

Troubleshooting

The properly functioning container with a CWM Modular System will have dry topsoil, and will not weep after 12-24 hours. The soil 2"-4" below the surface will be moist, but not wet.

Signs of Overwatering (a more common problem): Topsoil is wet or damp to the touch, or the unit continues to weep after 24-36 hours. Removing the stopper to check water level more often than necessary may lead to overwatering. To fix, repack soil solidly, adding additional soil if necessary. Plant sensor slightly deeper, making sure that the sensor is firmly packed in soil. Check that stopper is securely in the fill hole, and has been retightened properly. Allow soil to dry out until the topsoil is dry to the touch before refilling reservoir.

Signs of Underwatering (a less common occurrence): Reservoir level remains unchanged between fillings. Look for signs of water stress, and test moisture level at least 2" below topsoil for moisture (the plant may not have needed water). Remove stopper, watch approx. 3-5 min. to see if water level drops. If it does, system is functioning. Top water lightly. If level does not drop, top water plants and wait another week. Remove stopper again, observe water level. If water still does not drop, inlet holes at bottom of modules may be clogged, and will require removal of plants to open.

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