Also, you might be able to get a bit more flow by adding more of those washing machine filters at the top end, there must be a bit of flow restriction with them? Of course you no doubt have smooth curves rather than right angle bends in the piping, bends are bad news for frictional losses due to the turbulence they cause.
We banged the holes in the agitator of the washing machine to be slightly bigger (3mm with a nail and hammer). There is no restriction of flow there because if there was it would suck air in through the pipe we have put in for that purpose when the it occasionally gets blocked.
You can see that pipe lifting off to the right of the picture to a position above any high flood level. This means that if the whole system clogged up on the top it starts sucking air down the pipe (it also lifts from the end you can see on filter somewhat oas well as it fills inside with air) . The pressure drops to the turbines due to bubbles of air in the pipe and small amounts of air make it to the turbine end and I can record a drop in output. It is just a matter of turning off the system for a few minutes, the filter sinks into the water again (cleaned on top by the dried leaves just falling off with air) and it all works for another couple of months.
The F&P washing machines allow the megnetism on the stater to be increased or decreased to tune it to the conditions by twisting the nut on underneath. They make such good renewable generators that is is amazing that they are just thrown out!!
I have such a great supply of parts as well as tracker mentioned.
I am amazed how well it all works. I would suggest for anyone to go to their local tip and source a F&P smart drive washing machine to have a play with. They can be configured to run from voltages of 300volts down to about 20v making them very adaptable as Power-spout have obviously done.