Measurement of test substance. (A) For static tests, the concentration of dissolved test substance (that which passes through a 0.45 micron filter) shall be measured in each test chamber at least at the beginning (zero-hour, before gammarids are added) and at the end of the test. During flow-through tests, the concentration of dissolved test substance shall be measured in each test chamber at least at 0 and 96- hours and in at least one chamber whenever a malfunction of the test substance delivery system is observed.
Measurement of test substance. ( A) F o r s t a t ic t es t s, t h e co n ce n t r a t io n of dissolved t es t s u bs t a n ce ( t h a t w h ic h p a sses t hr o u g h a 0.45 m ic r o n fil t e r ) s h a ll be m e a s ur ed i n e a c h t es t c h a m be r a t le a s t a t t h e begi nn i n g (ze r o- h o ur , befo r e g a mm a r ids a r e a dded) a n d a t t h e e n d of t h e t es t . D ur i n g flow- t hr o u g h t es t s, t h e co n ce n t r a t io n of dissolved t es t s u bs t a n ce s h a ll be m e a s ur ed i n e a c h t es t c h a m be r a t le a s t a t 0 a n d 96- h o ur s a n d i n a t le a s t o n e c h a m be r w h e n eve r a m a lfun c t io n of t h e t es t s u bs t a n ce delive ry s y s t e m i s obse r ved.
