lol don i have already thought about most of the above...

yeh the fluid on the hose walls kinda is a worry.,..but i bet the resistance jumps big time....


the cap..been there..it has a presure release machanism in it...cant go drilling there...


optical...yeah now that has primise...except clear (or nearly clear liquid and opaque tank...did think about a laser to a photoresistor but i kinda doubt that the water would be enough to stop or obscure the beam...

cant go to the float idea (would love to) as i cant work out a way to accurately position it in the tank without drilling the dreded hole or glueing it(good luck on ploy prop). whatever i want NO chance of anything comming loose and making its way into the cooling galleries in th block...

thanks for the thoughts though...think i may have to just test bed it...