Close Look: Tunze DOC Skimmer 9430 DC

Trade News & Reviews

When it comes to skimmers, it can be easy to be led by the form of a product over its function. However, something that looks aesthetically pleasing doesn’t necessarily mean it will perform its primary role any more effectively. Sometimes it can be a challenge to look beyond the hype, especially when everyone else seems to be adopting the same technology and often having acceptable results. In this review we take a look at the Tunze 9430 DC which is perhaps one of the most under-rated skimmers on the market having been designed with quality and functionality as the primary concerns.

The first thing that strikes us about the 9430 is that it looks very different to the mass-produced cone skimmers that have been in vogue for the last few years. The straight edges of the main cylinder, which continue right through the collection cup, certainly aren’t unappealing though. To us the skimmer looks squat and powerful, and there’s a definite air of Tunze quality in the polished yet utilitarian design. It is this form that makes the 9430 a relative ‘shorty’ compared to similarly-rated skimmers too. Compared to the highly-rated Nyos Quantum 220 (which is not rated for systems as large as the 9430 can handle), the footprint is only slightly larger yet the height of the 9430 is around 10cm shorter. In our opinion, this makes it much more preferable for installations where the skimmer will be in a cabinet-based sump under the main display. The increased headroom isn’t the only thing the 9430 offers though. It has also been designed so the collection cup simply sits directly on top of the recessed, scalloped neck of the main chamber and this means it doesn’t need to be unscrewed or unwedged when you need to remove it. You simply lift it off! Seriously we can’t say how much easier this has made cleaning the cup. What was once a nightmare of twisting and slopping skimmate is now a quick and easy operation. Actually, removing the cup also removes the entire neck of the skimmer so this doesn’t have to be cleaned separately in the way typical of a cone type skimmer. This helps to ensure that skimming is kept at peak performance. Incidentally the collection cup holds 2 litres of skimmate so it’s pretty capacious and it also comes with its own cleaning brush which is also very effective.

Another key design feature of the 9430 is that, as far as we know, it boasts a unique ‘Anti-Overfoaming System’. Basically, this centres around a sealed intermediate space above the main reaction chamber that is created when the collection cup is lowered into place. This sealed chamber has a hole in the side and the air draw hose from the pump is connected to the chamber. This means that if the water level rises in the reaction chamber, it will spill out into the overflow space and, as it rises, it blocks off the air draw hole. This immediately stops foam production preventing potential flooding of the sump area (a common issue with many cone skimmers). It’s a clever, completely automatic system and during normal operation on an established tank it worked perfectly for us. We’d warn that it may not be enough to prevent an overflow during the break-in phase (on a new tank for example), particularly if the skimmer is standing too deep in the water, or the power is set too high. We found the sweet spot with our 9430 to be with the unit submerged so just the top few millimetres of the pump are above water level and the control dial is pointing mainly left (so operating at lower power rather than higher). Of course, this may work differently in other situations.

Moving on with the design and operation of this skimmer, it’s also worth noting the outflow arrangement. Basically, treated water exits the skimmer via a vertical pipe and spills over into a bracket assembly which holds a removable 300µm filter sock. This arrangement, again superbly thought-out, minimises any micro-bubbles exiting the unit and filters the water as a bonus. We actually use the ‘post filter bag’ as a handy location for activated carbon or GFO as it is extremely easy to access and service. We had a few micro-bubbles while the unit was settling-in, but far less than we’d have expected. Now the tank is more mature, there are absolutely no bubbles. Another major concern with a skimmer is the noise level and we can say with hand on heart that the Tunze 9430 DC is one of the quietest skimmers we’ve owned. Actually, out of around 15 skimmers we’ve used for protracted lengths of time on our test systems, the Tunze makes the top 3 of our list. Coupled with a solid, stable base and absorbing feet, the Hydrofoamer Silence DC pump is to thank for this and of course this means that the pump is also controllable. The controller device allows the pump speed to be adjusted smoothly via a small knob and feed mode can be entered by the press of a button. It’s simple and functional but works perfectly. The controller bracket is also of the highest quality.

Also available in non-DC form (9430) and with other models available (9415, and 9460 which has a whopping 5000lph air draw), the 9430 DC is, in our opinion, a superb quality skimmer that incorporates several design features that we really don’t know how we managed without before! They make owning and operating this skimmer a genuine pleasure. Skimming performance is superb and it’s the easiest skimmer to adjust we’ve ever had. We did have to raise ours using a skimmer stand but even then, it gave us far more headroom than an equivalent rated cone skimmer. To conclude, the 9430 affirms our belief that Tunze offer some of the highest quality reef equipment available and their quality and support is among the best in the business. The 9430 DC is currently available for an RRP of 606.70 GBP (incl. 20% VAT) and comes with a UK plug and a 2 year warranty.