Please note: this filter may have had a tray missing although they all seemed to fit together well the 1901 should have 5 trays, not 4 as shown in this video. Therefore it will take a total of 5.5kg of media, not 4kg as shown here. Thanks to Markus H and others for spotting that. JBL e1901 filter (Ebay): https://ebay.to/2RhdZkW JBL e1902 filter - new version (Ebay): https://ebay.to/2xSDi4B Taking a look at (and upgrading) the JBL e1901 filter which is for 'Aquariums between 200 litres to 800 litres'. This is a decent filter and although the 'pre-filter' tray doesn't add much to the filter it will extend maintenance times due to the extra coarse foams in the pre-filter making it a good choice for medium to large sized aquariums. Setting this one up is quite straightforward..... I only consider true filtration to be a full cycle which is the reduction of ammonia, nitrite AND nitrate hence the low figures - filters will not be nitrate factories when they are properly sized and properly set up. This series is all about trying to squeeze more efficiency out of internal and external aquarium filters which generally have a limited filtering capacity - If you have a filter you'd like me to feature in a video then please contact me on: sales@filterpro.co.uk 07772848730 (Richard) Anyone who sends a filter will have it upgraded and returned to them for free and the only cost you will pay is how much it costs to ship it to me - I'm helping to boost your filter and the resulting videos will hopefully be useful to viewers all over the world so it's a win/win. *Please do not send any filters without contacting me first as I want to try and cover every type of filter, not 20 of the same make and model* Due to the high international shipping cost I am currently only taking filters from the UK but I'm hoping that as this series progresses a useful database of knowledge will be built up which will help viewers understand how their filters work, the limitations and the steps you could take to improve filtering capacity and efficiency. The goal with any filter is to try and achieve FULL CYCLE filtration which is the reduction in ammonia, nitrite AND nitrate - if you look anywhere online you'll see people tell you that the nitrogen cycle in an aquarium ends with the production of nitrate which is removed by regular (often large) water changes. That is HALF the cycle and is done by AEROBIC bacteria which favors highly oxygenated conditions and is very easy to grow on any surface. The last part of the cycle (reduction in nitrate) is completed by ANAEROBIC bacteria which favors an environment which is very low or devoid of oxygen. It takes filter media with a very specific internal structure to support both aerobic and anaerobic ... https://www.youtube.com/watch?v=N67zF-Z-iy0