Operating Your Spec Aquarium Topless

Here’s an idea for an alternative way to setup your Fluval Spec aquarium: go topless!  That is to say, sans lid . . .

Going without a top is a great debate among serious aquarist, both for marine and freshwater planted tanks.  There are some compelling reasons to want to leave that acrylic lid off your aquarium, and also some reasons you might want to leave it on.

Spec V Aquarium with no lid

Advantages and Disadvantages of a Topless Aquarium:

The big reason that people want to run their aquarium topless is the aesthetics. It gives a great feeling of oneness with the creatures inside the aquarium.  Without a lid, you have a whole new dimension of viewing by being able to look down from above. In a planted tank, I think the view from above is gorgeous. I also love being able to see the ripples from water movement at the surface.

Spec V Aquarium Topless

Here are some other positive aspects to setting up an aquarium without a top:

  • Aesthetics: Topless aquariums offer a clean look, with unhindered views from above and no distracting elements above the rim.
  • Better Light Performance: Even clean glass can significantly block light from entering your tank. Dirty glass or frosted plastic (as is the case for the Fluval Spec lid) cuts down significantly on the light efficiency.  In the Spec, you do have the open area directly under the light, but you get better light performance at the edges of the tank if there is no lid.
  • Better Gas Exchange: Having a closed in aquarium with a lid hampers the exchange of gasses (Oxygen and/or CO2 depending on the day or night phase of plants).  Without a top, the water surface area is fully exposed and gas exchange is more uninhibited.  Although, with the hole in the Stock Spec top, this is not much of a difference.
  • Easier Access: When it comes time to feed your fish, you don’t have to work around the light to get at your aquarium. Freely drop in the food anywhere you wish.  If you have a planted tank, you can easily get your hands in quickly to trim and move plants about without having to mess around with moving and storing the top.
  • Simplifies Maintenance: It’s not a big deal, but that lid is one more thing to clean.  No lid; nothing to clean!
  • Runs Cooler: With greater surface area for air to freely flow over, the aquarium will operate slightly cooler due to evaporation.  If you run a cooling fan, it will work more efficiently with the top off for easy airflow over the water surface.
  • Attractive for the Spec: The Fluval Spec line of aquariums are rimless, with a nice clean edge of beveled glass at the top.  This look is similar to the ADA rimless tanks and it looks very nice without a top. The stock light, being attached to the end of the aquarium and not the lid, works the same with or without the top.

Spec V Aquarium Operating without a Cover

There are some very real arguments against operating an aquarium topless.  Here are a few to consider:

  • Jumpers:  Some breeds of fish are known to jump.  Even ones that are not known jumpers may one day decide they want to fly.  With no lid, they can careen out of the aquarium. Unless you happen to see it happen and can intervene, that fish is a goner.
  • Curious Critters: A close cousin to jumpers, some critters just like to crawl out of a lid-less aquarium. Nerite snails and Amano Shrimp are known to go for adventures outside the aquarium.  We had this very experience while operating without a top for a nerite snail who escaped and fell off our counter.  Poor lil’ fellah. Godspeed, Tiger. . .
  • Increased Evaporation: The phenomenon that makes the tank cooler, evaporation, also causes water loss at a quicker rate without a top.  This may or may not be a big deal depending on your maintenance schedule and the conditions inside and outside your aquarium.  If you live in a very dry environment, the tank may experience a rapid drop in water level.  This will require top-offs often, but even if you can stay abreast of the water level, adding tap water to top-off may increase the hardness for water in your aquarium.  Increasing water hardness will not be remedied until a partial water change is administered.  This rise and fall of water hardness may affect the health of your fish and inverts.
  • Exposure to Contaminants: With a lid, you have a bit of protection from stuff getting into your tank.  If you choose to run your aquarium topless, your water is open to the environment.  This means that unintended things can be dropped into the tank.  It also gives an unimpeded path for chemicals to enter from above.  If care isn’t taken, dispersal of cleaning supplies or other chemicals in the area of your aquarium will have an easier time entering the water column of a topless tank.
  • Risk of Equipment Falling in: This might be a longshot, but it is more plausible that a light fixture or other equipment over the tank will fall directly into the water if you don’t have a lid.
  • Wintertime Heating: What is a positive in the summer becomes a negative in the winter.  The additional water surface area exposed will allow more heat loss in the winter and will increase the load on your tank’s heaters.

The negatives are not to be ignored.  I can deal with most of the disadvantages to operating an aquarium without a lid, but the biggest downfall that keeps me from running the tank topless is the risk of fish jumping out.  I don’t know what the current inhabitants propensity for flight is, but I don’t necessarily want to test them.

Spec V Planted Tank without Lid

Having said that, for owners of a Fluval Spec aquarium, the lid is easily removed and stored for a time.  You can choose to display your aquarium topless for periods of time to try it out and can always revert back to the top on.  I certainly enjoy times that I have the lid left off; I love the look and enjoy having the ability to see the animals and plants from a new and beautiful perspective.

3 thoughts on “Operating Your Spec Aquarium Topless

  1. Hi, I’ve got mystery snails in my Spec V, so going topless is not an option. Even with the OEM lid, they get out. Any ideas for how to keep my mysteries in? Am open to other lids or mods to the OEM lid. Thanks!

  2. What’s the make and model of the light used in the pictures?

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