Power

The pumps are 240V AC and this is supplied via an inverter over the battery bank which takes 12v DC and changes it into 240v AC. (The inverter is not shown in the picture as I didn't have it when that pic was taken).


I decided to use 240V AC for a couple of reasons:-

1. I had already bought an inverter (on e-Bay) so that I could use 240V AC tools in the shed which is not directly connected to the house power supply. The shed contains a battery bank which was a cast off from the house some years ago and which is kept topped up by two 80watt Solarex PV Panels on the shed roof. The bank is twenty four 2Volt 560Ah batteries each of which weighs about 50kg. These batteries came out of a Telstra phone exchange and were part of a batch which included a bunch of duds- so I had to replace all them with new ones for the house supply- another saga in the life of an alternative energy enthusiast.

2. It has been difficult to find quality 12V sump/bilge pumps.

I have wired in a 240V AC outlet near the fish tank and this has the remote float switch plugged into it. This float switch bypasses the float switch on the new pump. The float switch is attached to a pole in the water and the levels at which the pump switches on and off are adjusted by changing the length of the tether on the float and the position of the ties on the pole.
It looks like the total power usage per day exceeds that generated by the panels so I have run a 240V line from the nearby pump house and have plugged a small battery charger into that line. This now trickle charges the battery bank and seems to be keeping up with the demand of the pump. The new pump should reduce the drain on the batteries significantly.
The pumping cycle now is pump on for about 8 minutes and then off for about 56 minutes. This gives about 22 cycles a day. Each cycle pumps about 750-800 litres a time so the total tank content is cycled through the growbeds about 4 to 5 times a day. In fact it is actually a bit more than that because the water is returning to the tank at the same time as the pump is moving it out. A quick experiment today suggests that the pump is actually moving about 10-15% more water with each cycle.