Jacob’s Blog

I was among a few people in the US to be the first to receive one of the new Tunze Master DOC skimmers. Mine is a 9420. It took me about a year to actually unbox it, get it wet, and run it. Around that time a few other people had theirs up and running and had realized that there were some performance issues with the pump drawing less air than specified and the skimmate barely making it up and over the neck.

Tunze first released a new pump, designed and manufactured by them, the Hydrofoamer Silence pump. There are a couple of sizes available depending on which skimmer it is slated for, the 9420.040 or the 9410.040. Roger of Tunze USA was kind enough to upgrade my original pump to the new Silence pump since I had never run it. More recently Roger sent me a new needlewheel which is said to improve the air intake.

I just installed the new needlewheel today and have fired the skimmer back up. I haven’t measured anything yet so I don’t know if I’ll see an actual improvement or not, but I can’t imagine Tunze would redesign the impeller for no good reason. I snapped a few pictures in the process of replacing the impeller.

First the NEW impeller:

Now the OLD impeller:

When I get around to testing the air flow I’ll share my results. Even with the skimmer running below the specified performance it still performs nearly as good as most other skimmers in it’s class, and is still more efficient than just about all of them (based on lph air/watt). I would also like to say that Tunze has provided first rate customer service - Thanks Roger!