Water Meter Reading: 10141.8
GreenHab Out: 2734.0
GreenHab In: 15778.9
TST level: 1/2 full
Tank #5: almost full

Plants in Good Health: 2 pots of Mint, 1 pot of Nasturtiums, 1 pot of Tomatoes, 1 pot of Peas, 1 Pot of Chives, 1 Pot with Unknown plants.

Plants in Poor Health: 4 pots of lettuce. One is looking a lot better than it did a few days ago. The other three are not showing as much change, but re looking no worse.

We discussed our difficulties with GreenHab water cycle management with Don during his visit. We explained that in the last several days we have seen a major discrepancy between water usage and water intake into the GreenHab (e.g. on 4/26/06, meters read 60 gallons of water usage, and over 200 gallons pulled into the GreenHab, but with a signifcant accumulation into the grey water storage tanks). Either we’re using more than the meter claims, or we’re not actually taking 200+ gallons out of the grey water tanks.

First, we suggested that perhaps the GreenHab intake flow meter might be malfunctioning. As a test, we closed off the valve downstream of the pump. We observed that the flow meter stopped, as expected. Don suspected that the meter is working fine, but warned that it is not accurate and assumes full volume flow when metering flow rates. A significant trickle of water through the meter would be seen as a very high flow rate.

To substantiate his claim, we inspected the two grey water storage tanks, and he observed that the bilge pump feeding water to the GreenHab was not operating properly (it produced very little water motion around the intake, indicating a low rate of flow). By thrashing the pump near the surface of the water, it resumed sucking water out at a more normal pace. But this only lasted for 5-10 seconds, after which it resumed pumping at its normal, low rate. Don asserted that we could not possibly be getting the flow rates indicated by the meter in the GreenHab, but that it is the pump’s fault, not the meter’s.

As a fix, Don suggested that we kill two birds with one stone. We mentioned that transferring potable water from the trailer tank to the permanent tank took around two hours with the current pump. Don found a brand new, high-volume water pump in the Hab engineering area, and suggested that we install it for potable water transfer. This would turn a two hour job into a 20 minute job. Next, we could replace the bilge pump in the GreenHab with the pump used for the potable water transfer. The configuration would be different – instead of having a submerged pump, we’d mount the new pump inside the GreenHab and pull grey water out of the storage tank. Since the new pump is not built to handle a large amount of silt, we’d also have to install an easily accessible filter upstream of the pump so that we could periodically clean the gunk that collected there.

We committed to at least the potable water pump changeout, and Paul made the installation in the late morning and early afternoon. We’re holding off on the GreenHab pump changeout until we first confirm that we want to have a non-submerged pump, and until we get the parts that will allow us to install a cleanable filter into the GreenHab intake hose.