many thanks for your reply, ye the pump has no adjuster its constant its a grow tank100 system all them are siting just level with the squares am only using root booster at min they wouldn be ready for any feed yet, plus there auto flowers which isnt good, i checked the ph its 5.7 which is ok he cubes are well moist, think my mistake was i didn put the bigger cubes in the propagter for while first which is why there so slow