The Hydor Seltz D is the venerable Italian company’s long awaited controllable return pump. Unlike virtually all other controllable pumps, the Hydor Seltz D is actually using a hybrid technology which allows adjustment of the rotational speed using a fully AC motor. In a market where most companies try to either build the ‘best’ pumps (usually expensive) or the cheapest (with lots of compromises), Hydor has staked out a unique position with their very practical Seltz D pumps.
By using an AC motor the Seltz D incorporates the best of both alternating and direct current motors including the aforementioned controllability, a quieter operation and reduced price since no power supply is required. The three larger Seltz D models range in price from about $180 to $230 with very respectable specs, and is probably about the best mid-range controllable pump for aquarium applications.
While the smallest of Hydor’s controllable pump models is currently the Seltz D 1600, there’s actually three more smaller models on the way! Due to their size the Seltz D 500, 750 and 1200 may not use the same hybrid AC control technology but these will offer the same quiet operation, reasonable price and adjustable output as their larger siblings. [Hydor]