Hi All-- We've been running some filters samples on a Costech ECS4010--fresh water phytoplankton. Supposedly these are fresh water, no preservatives, and filtered through standard glass fiber filters. However we've had problems with those samples eating holes in the quartz ash collector, the quartz wool, and sometimes the quartz reactor tube too. In the short term, extra quartz wool and an extra quartz tube in the ash collector minimizes damage. Has anyone else seen this, and if so, have you been able to trace the source of the problems? We've done other filter samples without unusual problems. take care gerry