Sparging problems

[rmuiritfc]

Hi i have purchased a mash tun (the cool box with a tap on) and have been given a sparge arm. Unfortunatly the sparge arm is too wide and cannot rotate inside the mash tun without holding it slightly above the box!!! I wondered if i need to cut this down or is there another way around this?
I have always had a problem with managing to get the full extract from the grain and have had beers with low og. What mash effiency should i be working to? i think the last brew was about 70% but i think i didnt mash with enough water. I have checked the booklet and it recommends 2.5 litres per kilo of grain is this correct?

[Bigster]

I usually mash with 2.5 to 3 litres per kilo of malt so 2.5 is fine.

If you have phils spinny sparger like mine then it would be fine to trim to size ( arms and spinner ) and just put the plugs back in the end.