The monitoring of biofouling is continuously evolving with new and better techniques being developed all the time. The major drawback of the currently used techniques is that these methods are complicated and time-consuming, involving culturing and counting of attached organisms. A continuously circulating batch culture system was therefore designed to study biofouling spectrophotometrically. Absorbance of bacteria attached to a glass tube was compared with direct counts done on DAPI-stained bacteria attached to 3CR12 coupons. Direct measurements of absorbance correlated well with the total counts obtained using the DAPI technique (r sq = 0.925). Spectrophotometry proved to be an easy, inexpensive and reliable alternative to techniques requiring laborious counting of microorganisms, for example the DAPI technique, for quantification of biofouling.