I think I fixed the reset problem

I added a NAND gate to the circuit and put it inline with the enable signal for the pump driver. This prevents the pumps engaging when the controlled is reset.

Something like this:

First controlled flow.

I got my first reading from the flow meter. The instructions reminded me to use the pull up resistor. The code is a bit basic.

Octave code for plot
times = [ 66.192 67.180 68.180 69.180 70.180 71.180 71.280 72.180 72.280 73.380 75.180 75.480 76.180 76.580 77.180 77.680 78.080 78.780 79.080 79.880 80.080 80.980 81.800 82.080];
ticks = [ 34 101 105 750 833 836 846 847 862 921 923 942 944 964 967 1018 1021 1072 1075 1132 1137 1196 1200 1266 ] ;
plot(times, ticks);

This isn't the best data but it's late and I want to go to bed. It's supposed to start with a low flow and then get to a steady state, this is to prevent the flow meter being overwhelmed. I'm sure at this flow rate that there is no real danger of that but it was the right idea to start with.
The k-factor is 1120, that is 1120 ticks per litre. Next time I shall see about measuring amounts.

Ready to get my feet wet

I bought a 12v relay from Maplin that will switch 240v to power the pump I have with a 10mm outlet. I have wired it all up and tested the switching action. Success. I've put pins on the flow meter (snipped LED legs) and made signal cables for the relay with more pins from an old Nokia power supply that had an inline step-up adapter.

Luckily I had a 3 pin mains socket, they wanted over £ for one in Maplin. Mine still has the 99p sticker from Wilkos.

That means I'm ready to start pumping some water.

Toodle Pip

The PVC tubing has arrived. It is 10mm inside diameter. I should have measured the darn pumps because although they look the same size they are, in fact, 8.5mm diameter. So I ordered some 8mm / 10mm tube which will be here next week. Good news is that it fitted the flow meters, which is the specification I took the measurement from. OOh, I happen to have a 600 L/H submersible pump with a 10mm fitting so I can commence the flow meter testing.

Regular pumps with flow meter

Because of varying head heights of the water storage, return from recycling, etc. issues I have chosen to use a flow meter to regulate water input. The idea being that all water input pumps can be pumping together and shut off once the required amount has been delivered. The flow meter introduces an additional complexity because the flow meter instructions say that the water speed should rise gradually and that air should be prevented from enterting the system. My pumps will be submersed so I'm not sure that will be an issue. For this discussuion that's not really an issue because that is a software problem likely to be quite simple by just modualting the control line.

The flow meter produces 1120 pulses per litre and takes a TTL supply voltage.

This circuit activates either pump, watches the flow pulses and then kills all pumps when the required flow is complete.