3d Printed Larval Kreisel Design

DaJMasta · Sunday at 9:46 PM

I've worked on 3d printing various kreisels for in-tank use but ultimately stopped because I wasn't having any success actually raising larvae in them. A bunch of experience, a bigger printer, and a bunch of different (mostly bucket based) designs, I saw a club member using a jellyfish tank to raise larvae and thought "I should try that again."

The result is this! I finalized the design in may but wanted to get some time using it and actually some results, and now that my kuekenthali shrimp are settling and I've had a few going for a while to maintain and use, I'm distributing the design for others to use.

This 3d printed shell fits inside of the Imagitarium (Petco house brand) 10 gallon rimless tank. You print the parts, glue in some fine mesh (my preference so far is 150 micron) to the windows, silicone the shell into the tank, and then finish setting up the plumbing and heating, fairly simple setup. The result is a tank with a 3-4 gallon kreisel area that keeps larvae in a slow, rotating suspension (and keeps food particles in unless very small), and a total volume of more than double that for some modicum of stability and dilution capacity.

At least so far, even without filtration I've been getting away with infrequent (slightly less than monthly) water changes and have still had pretty good results. Water changes are easy, though, as you can just siphon out the outer portion and replace it, leaving the larvae untouched in the middle. The side viewing makes it pretty easy to spot larvae with a flashlight through the top, and the opaque black shell blocks some stray light which will attract some larvae.

So if you have a decent sized printer and want to raise some larvae, give my design a try:
https://www.thingiverse.com/thing:7409430

And I've got a little tour/intro video here:

jonelder68 · Sunday at 10:54 PM

Very cool!

strich · 2026-09-14T09:23:39-0400

I'm always really excited when I see a new video drop from you. Thanks for keeping us updated on your cool projects!

I had my first clown fish spawn a few weeks ago (only lasted 3 days) and it's made me excited to start down this rabbithole myself.

The thing I'd love to see, is more of an in-tank or in-sump solution though - Take the kreisel design you've made and make it a hook on thing to the in or outside of a larger tank. Maybe even combine it with your auto catchment design.

Also is the size of the kreisel chosen just because the 10 gal tanks are available, or that you think the kreisel needs to be that big for what you're rearing?

Reef_Freak720 · 2026-09-14T09:42:18-0400

I thought about 3d printing a kriesel style larvae catcher based on the Vossen trap but never got around to designing them. Great work!

DaJMasta · 2026-09-14T09:46:40-0400

My early attempts a few years ago were just that - smaller and in-tank - and while the idea and simplicity is appealing, I think the reality is tough. While I don't think this design is the minimum for a lot of larvae, I do think there is a minimum - for example these Lysmata shrimp larvae can get almost an inch and a half long thanks to their lanky paddles, and some amount of length around the circle is probably needed to keep them in suspension reasonably. There's also just an observation that most breeding and scientific operations tend to use larger tanks, and that even when you are above whatever minimum is there, more volume means more larvae (concentration seems to be important and it could simply be that double the minimum volume means double the final larvae) and more volume means more fudge factor for water parameters.

As for why not in tank - I had a good amount of trouble with hydroids and a modest amount of other wildlife ingress. I went as far as to screen the water input and even run it through a UV to try and keep positive pressure with cleaned water in one of these in-tank options, and while I think there's probably a route forward there, it's a complicated, equipment intensive one. Starting a tank with a run from clean saltwater really reduces the chance something that will grow and eat the food or injure the larvae, like a hydroid, even without any sterilization or cleaning of the eggs/larvae going in.

The choice of tank was otherwise rudimentary - if you want a minimum gap to the glass to fill with glue, rimless is the preference (or derimmed, but I have broken a 10G doing that before) - and while 3.5 gallon buckets with inserts had been my go-to before this style, they did feel small, could parameter swing a bit with evaporation and feeding, so a 5 gallon tank kreisel seemed a bit smaller than I was aiming for. It happened that my printer could barely accommodate a 10 gallon as a single print, and that they were available and not so expensive.

The design can be slightly refit to other standard 10 gallon sizes, there should be at least a few millimeters in each direction before you have to redesign the spraybar, but these rimless 10s, while more expensive than standards, felt like a good price compromise. I think the tank, filament, pump, heater, and mesh sits around $70-75 when the tank is 50% off (which has seemed to be like 30% of this year).