We 3D Printed our own filter sock replacement cup.

So Chelle decided she wanted a seahorse tank at home, she’s been asking me for a tank for quite some time and finally i gave in. After looking after tanks all day we didn’t want something large to maintain not to mention the tribe of children and child’s toys make maintenance a pain so opted for the 20 Gallon (75 litre) Water box 20 Cube AIO (all in one) Tank.

The tank came with a strange size 2.75" sock, now I’m not sure how common this sock size is in the US but here in the UK 4" is pretty much the standard with some opting for the larger 7" sock and i think the Red Sea Max Nano Filter sock is an impressively small 2" so it wouldn’t fit.

Experience in the reefing industry and with filter socks generally has pushed our personal preference in the direction of filter cups rather than socks, you can fill them with media such as carbon or Rowaphos in a bag then place some filter floss on top of this allowing the cup to be multi use and easier to clean than a sock. Being that we couldn’t even easily get replacement socks here in the UK there was no chance of getting an off the shelf replacement cup at the correct size so we chose to take this opportunity to 3D print our own.

This sock is held in place in the tank with a small square acrylic insert which is removable. I remove this and measured it and the hole inside to design the replacement. After pondering about it for a short time I made the decision to replace both the sock and the sock holder with a single unit, after all whenever you tried to remove the sock, the sock holder came out anyway so a single piece unit would make maintenance easier.

The Design

Next up, i needed to design the new sock cup. Now we have seen many of these over the years from the original Acrylic manufactured items by Toby Hope at Little Ocean to the now off the shelf versions by red sea and Mantis brands so i had an idea in my head what the overall amount of holes etc. should look like for flow. Luckily in a previous life i had done CAD for a living designing architectural masonry for the house building industry so a little bit of custom design work didn’t phase me.

As i wanted to keep it simple i headed off online to use some online cad software called TinkerCad, it’s quite basic but for a lot of the 3D printed elements we use in and around the store its ideal. Quick and easy to use and all your designs are stored online so you can access them from anywhere.

I opted for a hexagonal pattern in the base of the holder (just because i fancied something different than circles) and then elongated slots to the side as many filter cups are designed.

I left the resolution of the cylinder rather low which gives it a faceted effect (something which i removed in version 2)

Printing

Once the design was complete i did a part test of the unit upside down so that only the sock holder part of the design was printed out. I then took this slither of print and test fitted it in the tank. Voila it fit first time (good job i learned how to use a ruler in school).

Knowing this fit the tank correctly i set to work printing the entire cup. Now you will see from the photos that 3D printing can by nature require what they call scaffolding, this is basically a printed support structure to hold your design as its printed. Because i had designed the sock and holder in a single unit a lot of scaffolding was required, this uses extra printer filament and takes longer to print but i felt it was worth it for the final result. I could have split the sock and holder apart and glued them later or just made the cup fit the original holder but this wasn’t what i wanted long term.

<3D Tech Info> For those of your into 3D printing, i chose for this first print to use PLA filament, i have used PLA around the store for simple things like egg crate legs and other items, while i know long term it will degrade most of the things we use get replaced every few months anyway

The result

Once printing was complete i had this big square looking thing, the filter cup was hiding inside there somewhere and i started to remove the scaffolding from the print, to my surprise it came off rather easily and i was presented with a nice shiny filter cup. I popped the cup into the tank filled it with floss and my work was done....

Version 2

Turns out, a customer also required a filter cup for a Waterbox tank, this time a 60 gallon cube, this size of tank happens to use the exact same size of filter sock that i had previously designed so i agreed to print the required two cups for this tank. However i took the opportunity here to re design the filter cup slightly.

The hexagon pattern was changed in the base of the cup, i added more hexagons for additional flow. I altered the upright cut-outs to have rounded ends (just because it looks nicer) and added a Kraken Corals name badge to the top.

As The customer was going for a red and black theme in his tank and sump we agreed to print these in a nice red colour to match.

<3D Tech Info>This second version was printed in PETG filament so its reef safe

For those of you that want to print your own version of this cup, or adapt it for different size you can download the STL print file from Thingiverse https://www.thingiverse.com/thing:4213751