The last layer of concrete has been in the pond two weeks, and the weather has been good, so it seems like time to have a go at filling it up. The pond plants are keen to get in there!
We need to test the integrity of the water seal and the efficacy of the pump.
Long ago we brought retic pipe up to the pond from a spot lower in the garden, near the clothes line. There will be a second pond in this spot eventually, and the pipe went in at the same time as the electrical conduit, which will bring power from the solar panel to the pond pump.
Over that time a creeper has grown over the two conduits so they’re no longer visible:
We attached a hose connector to the end of the retic pipe so that we could fill the pond from the water tank hose. I’m glad we did, because that pipe is now behind the wood pile. Good thing we can slip the hose through from outside to get them connected.
Now we’re good to go! We turn on the little green tap to allow water to flow into the retic pipe, and check all the connections in the pump box.
There were a couple of drips, but nothing major. The pipe clips were tightened to deal with it, but the drips were still a bit of a worry. The pump box is watertight to keep the rain out, but that also means that any water the drips inside has nowhere to go. Over time it could fill up. So we drilled a hole in the bottom and the little puddle of water that had collected in there drained away.
As predicted, most of the water went through the pump and out the screen at the bottom of the pond. A little bit was able to overcome the pressure of going up the hill, and came out at the top of the waterfall. Just a few drips.
I wasn’t sure that the water tank pump would have the head to get up there, but it’s doing OK. While the pond slowly filled, I went and fetched the solar panel.
It’s been sitting under the house for three years, so a bit of dust had to get cleaned off. The panel had been given to me many years ago when I worked in solar pumping. It was the only panel that had ever been returned under warranty, and no-one could be bothered sending it back to the manufacturer. One of the cells had burnt out, so I removed the cell and bridged the gap with wire. It works a treat, and the panel gets a 42V open circuit voltage.
I carted the panel up the hill, with the maximum power point tracker, the multimeter and some bits of wire and connectors.
… and it didn’t work. I could run the pump straight off the panel, but the voltage is too high. The pump was ramping up, with a satisfying rush of water through the tubes, and then cutting out, probably under instructions from its little power box. When a cloud came over the sun, the pump actually worked fine for a few moments. In full sun and with the pump at full pelt, the panel’s voltage is 39V. It should be around 24V.
The maximum power point tracker is there to regulate everything and protect all the bits. With 42V on the panel terminals it shows 20V on the battery terminals and -1V on the load terminals. Huh, it looks like it has to have a battery attached to work. Maybe the battery sets the system voltage, who knows. I don’t have a battery, so we’ll have to pack all the electrics up for the day.
I went inside and had some lunch, and when I came out again all the water was gone from the pond! I’d only filled it about 15cm; nevertheless that water should have stayed right where it was. All the valves were closed, and there was no sign of a leak anywhere.
The water level had dropped to the level of the screen at the bottom of the pond, so my guess is that it had gone out that way. I refilled the pond and put a plastic bag over the screen so the water couldn’t get out that way. Bad luck, the level is still falling. Looks like I’m going to have to seal all the pipe exit points with silicone or something. Sigh.