求翻译：添加磁粉的反应器在前5h内，pH急剧降至谷底，而无磁粉反应器下降缓慢，反映了磁粉对系统厌氧微环境中的产酸菌具有刺激作用，其数量和活性均高于无磁粉反应器。是什么意思？

Add magnetic particles within the reactor in the former 5h, pH dramatically down to the bottom, and the slow decline in non-power reactor, reflects the system of magnetic powder on anaerobic micro-acid-producing bacteria in the environment has a stimulating effect, its quantity and activity are higher than the non-power reactor.