Hydor Slim Skim Nano Skimmer Review

The Hydor Slim Skim Nano is one of the slightly larger and more affordable nano skimmers currently available.

Some seasoned aquarists feel it isn’t worth spending money on a skimmer for a nano aquarium. They believe nano skimmers are too small to create enough micro bubbles to pull out a significant amount of organic waste out of the water.

Instead they feel it is better to simply rely on water changes and put the money into coral, fish or something more enjoyable instead.

For the first 6 months of running my tank, I followed this advice. I would change out 4.5 gallons of water (a 20% water change) which would bring my nitrates down to about 12ppm. Then two weeks later they would be back up around 20-24ppm – at which point I would do another 20% water change.

Then I decided to try a skimmer.

I chose the Hydor Slim Skim Nano.

It was rated for aquariums up to 35 gallons – my nano is 24 gallons. And its dimensions fit the first chamber of my sump really well.

I’ve been running the Hydor Slim Skim Nano for 6 months now.

Here are my experiences with it so far:

Pros of the Hydor Slim Skim Nano:

  1. It has kept my nutrient levels much more stable. I am no longer seeing swings from 12 ppm to 24 ppm of nitrate between water changes. After adding it I only saw a swing of about 4 ppm between water changes. This was with no other mechanical filtration other than the Slim Skim Nano.
  2. This skimmer combined with the use of filter floss – has helped bring my nitrates down to 8ppm – and has allowed me to switch to smaller, weekly water changes of 10% (just 2 gallons) while keeping my nitrates around 8ppm without much of a swing in between.
  3. It is nearly silent other than a very slight hum – a great bonus considering my aquarium is in my home office where I work.
  4. The collection cup is easy to adjust, and easy to remove when it needs to be emptied.
  5. It’s magnetic suction cup mounts allow it to be set up in any aquarium or sump with a water depth of 10″ or more.
  6. It is quick and easy to disassemble and clean.
  7. It’s affordable.  The Hydor Slim Skim Nano is one of the least expensive nano skimmers on currently available.

Cons of the Hydor Slim Skim Nano Skimmer:

  1. While it did help to hold my nitrate levels steady, it did not help to continually lower them on its own. I had to add a second form of mechanical filtration – in this case, filter floss – to bring levels down. Perhaps some of those more experienced aquarists are right – nano skimmers may be too small to clean a ‘dirty’ tank on their own. They may best for maintaining low nutrient levels in an already ‘clean’ tank.
  2. The Hydor Slim Skim draws it’s air from inside the skim-mate collection cup rather than outside like some other skimmers (I haven’t yet figured out why…). When the cup is filled with a lot of foam, some of that moisture gets pulled into the air tube. As a result, the tube need to be blown out or cleaned out every few weeks or it may become blocked.
  3. The o-ring on the collection slides only has a slightly snug fit. This is both good and intentional as it allows for easy adjustment of the cup height. However, if you press too hard when putting the lid and air valve back on after emptying the cup, it will push the cup down and move it out of adjustment.

Here are a few shots of the skimmer in action:

Hydor Slim Skim water level for best skimming
Proper water level on Hydro Slim Skim Nano.

I’ve found the Hydor Slim Skim Nano works best for me when the waterline is between halfway and three-quarters of the way above the bottom of the entry slits.

The black rubber o-ring around the collection cup can be adjusted up or down depending on the bio-load of your tank.

If you have a lot of fish and critters start out with the ring closer to the bottom of the cup.

If you have a light bio-load start out with it closer to the top.

Every few days, adjust it a quarter of an inch up or down until you are producing the darkest skim-mate possible.

The best I’ve gotten it so far is the color of very dark tea.

Skim-mate produced by Hydor Slim Skim Nano
Skim-mate looks like dark tea.

More information on the Hydor Slim Skim Nano can be found at the Hydor USA website.