However, Kouassi et al. (2010) report the formation of precipitates. They quantified the glass loss using 40-μm filters (Kouassi et al., 2010). It may be that those precipitates were small enough to escape in their study, but – if formed during our experiment – be leading to precipitates decreasing filtration capacity by blocking the filter. This issue seems to be avoidable by neutralising the KOH solution prior to filtration. Short-term exposure to citric acid should not damage plastic polymers according to freely available on-line chemical resistance tables (e.g. Bürkle, 2017; TedPella, 1996–2019).