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Date Published - 22nd August 2012 - Published by - iQuatics Ltd

Dimming; is it all it’s cracked up to be?
Here at iQuatics we get lots of enquiries about dimmable ballasts and dimmable LEDs. Although dimming a T5 tube or a set of LEDs might give you a good visual look is it really beneficial to your aquarium inhabitants and do you know what you are doing to your equipment by dimming it?

Let’s start with T5s

There are now many luminaires and controllers on the market that allows T5 tubes to be run at a lower output than they are intended to be run at. This might produce a great visual effect to the aquarist but it has a detrimental effect on the performance of your tubes. By restricting the current that reaches your tubes you are in effect forcing them to under run. By under run what we mean is that the gases inside the tubes don’t get excited enough to make the phosphors glow at the correct manufacturer’s specification. This means that the light given off by the bulb is not in the spectrum advertised. This will reduce the lifetime of the bulbs and speed up the shift in spectrum that is found with older bulbs. This means that instead of replacing your bulbs every 6-8 months as recommended by most manufacturers you may find yourself needing to replace the bulbs every 2-5 months.
There are other ways of achieving the look of moonlight using T5s without the need for dimming and damaging your tubes. A simple solution is to have the ballasts on separate timers if possible, allowing you to have different banks of light on at the desired times. This doesn’t necessarily have to be done by adding lots of unsightly cables, taking the iQuatics’ AquaLumi Series 2 as an example; we have added a single cable with twin plugs that allows 1 bank of 2 tubes and 1 bank of 4 tubes to be run independently, allowing you to create a night time effect. We must stress it is not easily achieved with T5s no matter what functionality you have.

Now the LEDs

We’ve all seen the LED controllers that provide you with fantastic looking storm patterns and the like, again visually to the aquarist this is a cool feature to show off to your friends at dinner parties. In reality these again have a detrimental effect of the longevity of your LEDs. In the same way restricting or increasing the current to a T5 by restricting or increasing the current to your LEDs you are forcing them to under/over run.  Over/under running an LED can have a dramatic effect on the LED. Many of the LEDs used in aquarium lighting are designed to run at 350ma as factory recommended. We have found that some units are running LEDs at 700ma; that’s double, which in turn means half the lifetime of the unit! By dimming your LEDs you are greatly reducing the life expectancy of the unit. We are finding now that people who have purchased the early LED units have found a huge drop in performance and the shift in spectrum given from them.  This in essence turns the LED into a different bulb, as you are now producing a spectrum of light that is not the one the LED was designed for; in turn this can create a problem with nuisance algae.  If there is a constant current running through the LED then dimming it will not affect the life of the LED; however the extra heat generated can have an impact on the longevity of the unit.

There is another way!

There is another way of producing these effects with LEDs that doesn’t involve dimming; it’s the simple on and off process! As mentioned in the T5 section it is possible to have different banks of LEDs and these banks can be set to come on and off at set times, so different colours (or numbers) can activate independently. This allows the LEDs to run at the correct temperature and spectrum that they were designed for.

Do your aquarium inhabitants really enjoy it?

There are many reports of storm patterns being ideal for inducing spawning in fish and corals, in reality this is just sales patter. The one thing we have found with our research is that people running dimmable LEDs and T5s had increased instances of fish stress and out breaks of diseases such as white spot.
You have just read another great aquarium blog post by iQuatics. If you would like us to blog about a specific subject or have your own aquarium blog content you would like published on our website, get in touch. Together we can help grow the iQuatics aquarium blog into a vast resource full of combined industry knowledge.

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