There are several kreisel tanks on the market at the moment, and the complete range from German manufacturer Schuran, now distributed in the UK by Seneye, is impressive, says Dave Wolfenden.
The term 'kreisel' comes from the German for' merry-go-round', hinting at the fundamental design difference between these specialised systems and the traditional aquarium. The emphasis here is to generate a circular flow of water (or gyre) to keep pelagic organisms in suspension. Kreisels can be used for the culture of larval fish, raising certain juvenile seahorses (such as Hippocampus erectus and H. reidi); and they’re a must for the keeping of many species of jellyfish, for which air bubbles are a no-no and specific current patterns are vital.
Schuran offers two main designs of kreisel, with the smaller 'breeding' models available in 20, 30 and 45 l/4.4, 6.6 and 10 gal in volume, with diameters of 30, 40 and 50cm/12, 16 and 20in respectively. The so-called ‘show’ kreisels are larger and more expensive, primarily aimed at public aquariums.
I’m using the medium-sized model and circular water flow is facilitated by the curved design of the internal acrylic surfaces and the placement of the adjustable spray bar. This creates a sheet-like laminar flow around the edge of the tank, helping to keep the inhabitants drifting in the current. It’s important to have fine control over the flow, so installing a valve for this purpose is essential.
The high surface area of the grille at the rear face of the tank’s internal wall means that delicate drifters won’t get sucked through, with a pad of foam providing additional security. Let this accumulate a bacterial population and clean it out in tank water only, and it will also act as a biological filter, useful if running in stand-alone mode. The grille had one or two sharp edges, which I feared might present a risk to jellies, but these were easily smoothed off.
Highlights of the product include:
Build quality: These tanks are very well made, with the acrylic expertly glued and edges polished to a high standard.
Neat, clean and compact design: In the centre of the rear panel of the main section is a grille, allowing water to flow into a smaller section behind. This rectangular compartment is fitted with two drilled holes: one for the spray bar and the other to be used as an overflow, for which you’ll need to source an appropriate bulkhead/tank connector fitting. The spray bar slots into a tank connector (supplied), and 20mm PVC pipe can be glued in place here for connection to a flow pump if you’re planning on connecting the unit to a sump.
Can be used as a stand-alone unit: This is possible by plugging up the two holes and installing a small powerhead in the rear compartment, with some judicious pimping of the spray bar to connect to the pump. There’s even space for a small heater and additional biological media if needed.
Can be plumbed into a sump: For breeding systems, that’s a very attractive proposition: the kreisel can be set-up remotely from the broodstock tank, yet still use the same water – add a tank connector and plumbing to overflow water to the sump, and add suitable plumbing to return the water to the kreisel via the spray bar, and hey presto! Alternatively, two or more kreisels can be linked to a dedicated sump, allowing for a systemised approach.
Cleaning is a cinch: This is important, as jelly systems need regular removal of biofilms and ideally bleaching for optimal health, so being able to strip down and deep clean is important. Reassembly is just as easy as taking the tank apart.
- Great build quality.
- Simple, effective design.
- Easy to maintain.
- It’s expensive.
- Additional plumbing will be required to get the tank up and running.
Price: Schuran medium-sized kreisel 30 l/6.6 gal, £456,
More info: schuran.com or tel. 01223 911075.
Why not take out a subscription to Practical Fishkeeping magazine? See our latest subscription offer.
Don't forget that PFK is now available to download on the iPad/iPhone.