I am attempting to deal with the hassle of culturing brine shrimp nauplii by using biological filtration, e.g. a sand bed along with macro algae. Assuming the net area works, the next step is to get a much larger tank with a deep sand bed, a protein skimmer, and more macro algae.
I’ve been raising a lot of Artemia nauplii to try to feed the jellyfish. I’m looking for ways to keep the food “fresh” as I’ve noticed that dead nauplii in the refrigerator begin to rot fairly quickly despite the refrigeration. I am assuming this is because the nauplii are so small, even with reduced bacteria growth it doesn’t take much to ruin them. Since nauplii take a relatively long time to culture (72 hours from hatching to enrichment), it’s important to keep them alive as conveniently as possible. Most guides I’ve seen online admit that nauplii are tricky and labor intensive to keep due to their small size and the large amounts of waste their fast metabolisms generate. Commercial operations seem to simply use economies of scale, with huge vats, light based harvesting (you compact the nauplii using bright lights and just siphon them out), and bleach to clean equipment between batches.
My idea is to try to use a biological filter (such as an existing saltwater tank) to filter out all the waste from the nauplii harvesting. I would store the nauplii in multiple mesh storage cubes that are submerged in the larger tank. These mesh cubes are based on fish breeders, in fact I took a frame and had a friend make a replacement bag out of 105 micron opening mesh material. The goal is to eliminate some of the water changes that were necessary for growing, feeding, and enriching the nauplii. I could see the system handling the growing to instar II and feeding stages. All the waste material will be filtering in the tank, and any decaying material will simply be mineralized, and then consumed by the macro algae. Organic waste from the algae will then be exported via protein skimmer. Hatching will still require a specialized vessel, and enriching would still need a separate system as well.
In the end, I will have a large 20+ gallon culture tank that has enough room for a sand bed to hold nitrifying bacteria, Chaetormorpha macro algae, a protein skimmer, and 4 or 5 of these mesh storage cubes. Each cube will hold the nauplii of a 2L hatching cone, or approximately 4g of eggs (or 400,000 to 500,000 nauplii). Each batch is pipelined and fed through the common holding tank; whenever I need to enrich for feeding, I’ll take a mesh cube out, dump it into an enrichment vessel, and then harvest and feed. This potentially eliminates one third of the water changes required, but most importantly it recycles water. I can hatch the nauplii by taking water out of the culture tank, and I can simply harvest the nauplii by draining back into the tank. So long as the total volume is enough not to ammonia spike, the system will absorb and export all the organic waste.
The potential downside to this approach is it’s complicated and you could crash the tank. Once you get an ammonia spike and nuke your harvested nauplii, you would have to hatch new batches and have several days without food. The other thing is if you introduce parasites or undesirables into the tank, it’s possible your nauplii (and their water) will be polluting whatever you feed them too. This is the only reason I think this approach is not used commercially but it would still be viable at home since you have ultimate responsibility over what goes into your tank.