The Achilles Heel of Bubble Magus Skimmers

The following warning applies to the NAC6 skimmer with the Atman 2500 pump but may apply to other Bubble Magus protein skimmers with Atman pumps. Caution should be taken when assembling and cleaning these skimmers, particularly when screwing the air intake on to the impeller cover. The impeller cover is the Achilles Heel of the NAC6. The threaded shaft on the cover is less than 1/16" thick plastic. It actually expands when the air intake is screwed into it. The instructions state not to screw the air intake more than 2 turns into the cover. There is a reason. The shaft will crack.


A stress fracture already present on a brand new impeller cover

When the shaft cracks, the air injection is compromised and you will have a dead skimmer.

Translation: If you over-tighten the air intake, the impeller cover shaft will break.

My first question for the manufacturer is 'Why does the shaft have a lot more threads than needed then?' Having more threads easily allows you to over-tighten and break the shaft. My second question is 'Why is this critical piece less than 1/16" thick?' If it were thicker, this would not be an issue most likely.

Note the stress fracture already present in the shaft of a brand new impeller cover pictured above. This shaft will no doubt crack at that fracture line if I over-tighten the air intake expanding the shaft.

YES - I did break my original one. In a heatwave with 90 degree heat. Not a good night.

My pump would not restart after a power failure - signaling a cleaning was needed. A typical experience I've found with a variety of pumps. I disassembled the skimmer, cleaned and reassembled the skimmer. In hindsight, a bit hastily as I was worried about my tank in the heat. I was unaware that I over-tightened the air-intake - I was on auto-pilot and screwing a part in until snug. When I turned the skimmer back on, I was flabbergasted to see only a trickle of air in the reaction tube.


HOW TO FIX IT IF YOU CRACK THE SHAFT:

After swearing up and down for 20 minutes, this is how I fixed my cracked impeller cover...

1. Remove the impeller cover and dry if needed
2. Screw the air-intake back into the cracked shaft until cracks have spread
3. Crazy glue into the cracks - try to just get the glue between the cracks and on the outside of the shaft - not on the threads of the air-intake inside
4. Remove air-intake and clean off any glue quickly
5. Put more glue on the shaft over the cracks and on the top edge of shaft
6. Put a light amount inside the shaft
7. Allow to dry

After gluing between the cracks, when you remove the air-intake, the shaft will retract bonding the glue in the cracks.

After drying and carefully reassembling my Bubble Magus skimmer, it worked once again and I was relieved. A broken skimmer at 9pm in 90 degree heat would not have been a good thing for my aquarium.

I ordered a replacement impeller cover as a backup. Since it came with a stress fracture already present, I am officially declaring the impeller cover the Achilles heel of the Bubble Magus NAC6 and possibly other Bubble Magus skimmers.

WORD TO THE WISE.

Disclaimer 1: My replacement impeller cover came well-packed in the mail. This was not a shipping issue. I believe the crack shown is the result of poor quality control with this part and the fact that it was allowed to be made so thin.

Disclaimer 2: I STILL feel that this is the best skimmer I have personally owned. Overall I am extremely happy with it and it's performance for $158 delivered to my door. The rest of the parts are surprisingly very high-quality for the money. It is truly just this ONE PART - this one CRITICAL part that needs addressing.


I hope this helps someone else...


matt

More pics-

The blue air intake piece on right:


The Bubble Magus NAC6:


Bubble Magus NAC6 thread with more pics and info:
http://www.3reef.com/forums/protein-skimmers/bubble-magus-nac6-skimmer-unboxed-77380.html

 

informative. thanks.

 

I wonder what other BM skimmers use this part?

You could probably fit a spacer to not allow the coupling to be threaded in more than 21capable turns.


I'm looking into a more efficient skimmer than my skimmer I have now. MAGUS's are one brand I am looking at.