We were maintaining our reef tank on the weekend when we realized that one of the unsung heroes of reefing was sitting there in our sump, right before our eyes. Furthermore, it’s been running trouble-free for 10 years. Here’s why we think it’s so good.
The Curve 3.5 protein skimmer by Bubble Magus is a low-priced, compact AC skimmer designed to sit in a sump and function on reef systems up to 300 liters. After ATB, and Vertex, Bubble Magus was one of the front runners in China to adopt cone-shaped acrylic bodies and finish their skimmers in fetching red and white, as well as placing the pump underneath the skimmer body to save space.
This meant that when we got our hands on one ten years ago it was small enough to sit inside the sump for an 18” cube tank and because of its compact size, we’ve also used it in 24”, 36” and even 60”, 500 liter/132 gallon systems and it always skimmed well, in a huge variety of situations, load, and water depth. It’s short too at just under 18” tall, meaning that back then it could also be accessed inside a short cabinet.
It’s powered by an 8W Rock SP 1000 AC pump with needle wheel impellor and has just one point of adjustment – a good old rotating standpipe whereby you turn it one way and water rises up the neck, and turn it the other, and the water level decreases. Simple, and when we talk about dialing-in skimmers these days and maybe taking a few days and several points of adjustment to get it right, this skimmer was simply set and forget, and it’s been running so sweetly ever since.
With everything we know about protein skimming, it’s all about creating as many bubbles as possible, as small as possible, and holding on to them inside the skimmer’s body for as long as possible to form the best skimmate. That’s why some manufacturers still stick to an external pump injecting the air/water mix into the bottom of a tall skimmer body in order to achieve the best results.
Look inside the C3.5 however and the air isn’t even released until two-thirds up the skimmer body, and the reaction area is only 4” high. The pump only takes in a maximum of 300lph/79gph of air and everything about this diminutive model should say low performance. But it’s brilliant, and right now it’s skimming as thick and as dark as it ever has, and that’s with it running downstream of a Clarisea Gen 3 Roller Filter.
Speak to anyone about Bubble Magus skimmers and most will say the pumps die. We sold BM replacement pumps in our retail days but again this one has never missed a beat, it goes about a year without us maintaining it and in that time the inside of the skimmer became its own ecosystem with fan worms, and mysids charging around the cone. We have never replaced the pump or the impeller.
10 years on, there aren’t many bad protein skimmers available, and most skim well. We’re confident we have used at least 75% of what’s available now and despite the addition of DC pumps, app control, cup cleaners, and float switches, pound for pound, the BM C3.5 is still one of the best in its size category and when you factor in its low retail price of sub £115/$140, and its 10-year longevity, it’s the best small, low cost, sump-based protein skimmer we’ve ever used. And it’s still going strong.