The push to make bioassays more sensitive has meant an increased duration of testing to look at more chronic endpoints. To conduct these longer bioassays through the use of traditional bioassay methods can be difficult, as many traditional bioassays have employed manual water changes, which take considerable time and effort. To that end, static-renewal systems were designed to provide researchers a technique to ease the manual water change burden. One of the most well-known static-renewal designs, the static intermittent renewal system (STIR) was produced by the United States Environmental Protection Agency in 1993. This system is still being used in laboratories across the globe today. However, these initial designs have become rather dated as new technologies and methods have been developed that make these systems easier to build and operate. The following information details changes to the initial design and a proof of concept experiment with the benthic invertebrate, Chironomus tepperi, to validate the modifications to the original system.

推动生物测定更加灵敏的努力意味着增加了对更多慢性终点的检测时间。通过使用传统的生物测定方法来进行这些更长的生物测定可能是困难的，因为许多传统的生物测定都采用了手动换水，这需要花费大量的时间和精力。为此，设计了静态更新系统，以为研究人员提供一种减轻手动换水负担的技术。静态间歇更新系统（STIR）是最著名的静态更新设计之一，由美国环境保护署于1993年生产。该系统至今仍在全球的实验室中使用。但是，随着新技术和方法的发展，这些初始设计已变得过时，这些新技术和方法使这些系统更易于构建和操作。Chironomus tepperi，以验证对原始系统的修改。