Fluval Flex Aquarium Filter Mod with media baskets

thingiverse

After purchasing a Fluval Flex 35l/9g, I quickly identified some drawbacks and opportunities for customization. I decided to redesign the filter system to optimize its performance. This is Part 2 of my project. The entire project will focus on improving cooling, heating, lighting control, water refill, and other features using an ESP microcontroller without modifying the tank's hardware. The original filter has a peculiar arrangement of media, which I plan to rectify. Typically, water flows through mechanical filtering first, then biological, and occasionally chemical (like active carbon treatment or nitrate removal). However, in the original setup, the water primarily passes through the mechanical filter and may or may not touch the biological or chemical components. To address this issue, I designed an insert to replace the original sponge block. The new design features three separate baskets that ensure a top-to-bottom flow direction. At my current setup, the middle basket contains EHEIM substrate pro, while the upper one holds a piece cut from the original sponge. Above the upper basket, I loosely packed filter wool. Additionally, I included half-height baskets to combine filter mats or fleece. For me, this configuration works flawlessly, and the EHEIM substrate outperforms the original Fluval bio filter by a significant margin. Nitrite levels consistently remain below 0.2mg/l (ppm). To print the models, use the provided STL files in their specified orientation. Rotate the case 90° around Z if necessary. All models can be printed without support. Print the following components: 1x Case 1x Handle 3x Basket (or 2x Basket_half for 1 Basket) Insert the baskets with small holes facing towards the open side of the case. The Case should be inserted into the tank with intake holes to the left, not the side where the pump is. Use PETG, PA, or any other food-safe material and water the model for at least 24h before inserting it into the tank. If you plan to switch bio filter media, insert the new one in the lower basket and the old one above. Leave this setup for at least 4 weeks before removing the old one. A huge thank you to Trigg-Darren for providing the dimensions of the 57L and testing my design! [UPDATE 13/JUN/2019] * Added half-height baskets * Small correction on basket_57 Published project parts so far: + Fluval Flex Cooling Fan Adapter 40mm https://www.thingiverse.com/thing:3640543 + Fluval Flex Cooling Fan Adapter 80mm https://www.thingiverse.com/thing:3671625 + Fluval Flex Filter Mod https://www.thingiverse.com/thing:3639353 + Suction cup temperature sensor mount for DS18x20 https://www.thingiverse.com/thing:3640844 + Water level controller hose clip for Fluval Flex filter compartment https://www.thingiverse.com/thing:3675744 + Fluval Flex Intake Pre-Filter / Baby-Safe https://www.thingiverse.com/thing:3730658