We have a mixer shower in the ensuite and the pressure is very low.we have a pump in the hotpress and the pressure gauge is at 1. we already have an electric shower in the bathroom and as the ensuite is recently being done up I don't want to buy a new shower. Are pumps at different strengths. would we need a stronger pump. We had a plumber out recently and he inceased the pressure on the pump but pressure is still very low. we are on mains water. any advice would be appreciated.