Many hobbyists ponder the question of how useful covers for aquarium tanks actually are in the long run. There are certainly quite a few issues to consider before deciding which is the right set-up for your aquarium and the main issues with keeping  a tank uncovered or covered need to be weighed up because there are positives to both scenarios…as well as negatives!

The positive aspects of an uncovered tank
An uncovered tank allows light to fully enter the water…and all aquariums need that! There may also be issues with gas exchange on covered tanks…which can cause PH levels to drop. So in theory, an uncovered tank can be a healthy tank.
The negative aspects of an uncovered tank
Tanks which are uncovered do suffer from more evaporation. If your water levels are creeping down then this can and does cause issues…particularly in salt water tanks where the salinity will rise as the water dissipates. Uncovered tanks are also at risk of dirt and other foreign objects having an easy entry point. If you have pets such as cats…or if you have children then leaving your precious tank open to their interference may not be the best idea! If fish are startled there is also the risk of them jumping out of the water in an uncovered tank…at best this can result in an injured and distressed fish and at worst a dead one.
How to decide if a cover is right for your tank
When a tank is covered, water collects on the cover and then drips back into the tank…keeping water levels (and salinity levels) stable. Without a cover that water is taken off into the atmosphere and owner’s will find themselves carrying out regular “top ups” to make up for the loss.
Some people prefer to rig up their own covers from porous materials….fine grids work well as they allow light to penetrate, stop problems with gas exchange occurring and also keep the fish where they belong…in the water! Some people find that a mesh material works best and mesh that is stiff enough can be found at large art supply shops or at large DIY shops for very low prices.
If like many hobbyists you do decide to plump for a cover and choose a glass one, you will find that there may be some issues with water marks or salt residue building up on your cover…this doesn’t look pretty but is easy to clean off and if you do this regularly then you should not find that it is a problem. A cover will also keep the heat at a regular level as well as protecting any lights or reflectors from salt splash.
As many hobbyists discover, finding out your preferences is sometimes a matter of trial and error…weigh up the risks and the benefits and see which set-up suits you and your fish best. The indications are that a cover is preferable and that both the fish and the water will be in better condition if a cover is present!
You have just read another great aquarium blog post by iQuatics. If you would like us to blog about a specific subject or if you have your own aquarium blog content which you would like published on our website, please get in touch. Together we can help grow the iQuatics aquarium blog into a vast resource full of combined industry knowledge.