Does your aquarium have too much light?

I suspect in many cases it does.

The market is definitely light obsessed and that is a guarantee. Whilst I would agree the more light you have the potential for better growth exists, you have to balance that off with everything else going on in your tank at the moment.

Let’s look into powerful lighting now and what might be causing you issues. LEDs are pummelling the market and rightly so – they are very effective, cheap to run and pack a punch in terms of lighting, but the BIG question is how much light does your tank need and when you pummel your tank with light, are you increasing everything else like fertilisers, CO2, water changes, water circulation etc? I know when I first started using more powerful lighting, I didn’t make this correlation and very quickly ran into troubles, and I’m keen for you to avoid the mistakes I initially made.

Before I go into this a little more, let’s take a trip down memory lane. In the days before modern lighting, hobbyists would illuminate their tanks with T12 lights – that sounds funny just writing it! T12s were clunky, chunky and not particularly effective and were soon superseded by T8s which are still sold in the market today. When Takashi Amano (google his name if you don’t know who he is) was creating wonderful aquascapes in the late 80s and early 90s he used huge amounts of T8s over his tanks and I remember reading (being slightly astonished) that he was using 12 x T8s over a 200cm tank. I just couldn’t believe it. I was running 2 x T8s over my 120cm tank… But it probably won’t surprise you that back then, algae issues weren’t really there. Sure people got algae but it wasn’t anything like it is now. Saying that, I can bet you anything you have some sort of algae battle going on in your tank, whether it be hair algae, brush algae, brown algae – the list is endless. But I also suspect you may have quite a lot of light in your tank; you may have even introduced LED lighting hoping that was the answer to some of your aquascaping prayers in terms of plant growth. So the question begs – why weren’t hobbyists getting the algae issues back in the day that they are today? The simple answer is most probably down to lighting.

T8 lights are not particularly powerful and this is why to get real success, you had to use quite a few (in Takashi Amanos tank, 12). Today, the majority of hobbyists use T5s which are more powerful and as a result you need less of them. Juwel tanks for example use T5 lighting – this is what people want and Juwel have taken note and changed their manufacturing. We all want more light yet most of us struggle to handle it. T8s will struggle to penetrate water and if your tank is any more than 30cm you will be familiar with this. So is more light better? This really depends on what you are trying to achieve.

You only need to do a little browsing online to see lots of wonderful aquariums and some are super dooper – you know the type that really has the X factor. You look at it and think I WANT IT!!! You compare your tank to theirs and one main difference is the amount of light they have to yours. They’re probably using a lot of light, LEDs and T5s – some may even use metal halides. But the difference is, the tanks you see in magazines that impress you, the owners of these tanks aren’t new to the hobby. They have probably had a very rocky road to get to where they are now and they certainly know a lot more about lighting than they did at the beginning. They will have failed many times beforehand. They also know how to create a balancing act and that high lighting means high everything else because you can’t have one without the other.

You’re probably reading this wondering about your tank and if you do have too much light? If you are, you have one of two choices. You either reduce your lighting intensity by elevating the lighting from where it is now, or you crank things up a touch and you start raising your game.

High lighting is the equivalent of putting your foot on the accelerator. In a fast car, you need better than average breaks otherwise the higher the speed you are travelling at, the harder your breaks have to work in order to stop yourself from crashing. In the aquascaping world, you can crash very easily – your tank can quickly become full of algae – this happens fast because you have high lighting (fast car analogy). Slow things down a bit (take your foot off the gas) and you have more chance to react to any changes that you are making and how your plants are reacting to what you are or have done. Remember in this game we want to cruise – we want to arrive without crashing, we want to enjoy the journey, look out the window and appreciate the views. We’re not racing because we’re not in a rush and we know what happens if we go too fast right?!

So my final nugget of the day is this – high lighting is only suited to hobbyists who are experienced. Specifically those who have tried many times and failed and tried again. They got there in the end because they learnt so much and they know the balance is a fine one. They started slowly and so must you. Keep your lighting down to a minimum, make sure the intensity is not too high & that way you won’t be in for any surprises. Any changes that you do make will be slow and steady which is what the plants want anyway.


11 thoughts on “Does your aquarium have too much light?”

  1. Hi Richard,
    Thank you for the post. I am wondering if that is what is happening to me right now.

    I am a beginner at all of this and for Christmas I got a 26 gallon tank (my previous tank was only 13 gallons and just fish). I ordered a bunch of plants online that were supposed to be easy to grow. I planted my plants of 2/3/3014. Well, things have been going downhill ever since. I googled until I was blue in the face and decided I needed more light. I bought the Marineland Aquatic Plant LED Lighting System. That was about 2 weeks ago. A week ago, I added 10 root tabs, and I continue to use Flourish a couple times a week.

    The plants just seem to be barely hanging on and now I am growing algae faster than ever. The columba keeps getting uprooted and nothing looks healthy (except my fish seem to be doing ok) and everything is being covered with algae !!!!

    It’s been less than a week since I’ve done a 20% water change, and my tank is really looking bad. HELP! What are my next steps. You are right about looking online, everything seems so easy to do and beautiful.

    Any tips on what my next steps should be?

    Can anyone help as to what my next steps should be?

    1. First step = more research. I’ve replied to loads of posts just like yours so browse the blog for answers.

      But you have too much light and not enough fertilisers. You also need to be doing lots more water changes.

      Sign up for my weekly 60 second newsletters, friend me on Facebook and twitter. I’m always posting on there – useful stuff everytime.

      Download my free ebook off the home page. All the answers are there but you have to do some digging first.

  2. I bought a second hand tank and swapped the old tubes for LEDS. I had an algae bloom initially which sorted it’s self out but for a while now I’ve been battling with some dark fluffy algae that sticks like sh#t to a blanket. I’m going to turn one of the lights out in hope.

    1. LEDs are very powerful and when you change something like lighting, everything else needs to be increased with it, so more fertilisers, more water changes more liquid carbon etc

  3. i bought an Led lamp type enclosed fish tank now it has stuck on the light and i cannot get it off even at night will this have a negative impact on my fish .im a novice at fidsh keeping any help appreciated

  4. Hi Richard i am still a novice at fish keeping and have made a few mistakes along the way and one of them is lighting. I changed the T5s for an aqua one jbar which fits my juwel rio 180, but i do get algae problems mainly bba and staghorn now and again. I do regular water changes weekly 50% and use fertilsers along with liquid carbon.

    I think the light is to strong compared to the T5 lighting and i wondered if you agree with that and maybe i should switch back to the T5s.

  5. I struggle as a beginner with a juwel nano tank (30L) with Led as lighting. Even with only 5W, the led tube is very powerful and bright, a lot more than what I saw here and there.
    I was indected with brown alguae (diatoms), at a point you cannot imagine. I just tried everything, measure all parameters of the water, tried anti alguae, flourish excel and so on.
    I ended up taking care of the lightning since it was the only think I never tweak, putting several layer of paint tapes on the leds. Light is now lower and more yellow, I always have some diatoms but in control some way.
    What I read here confirms what I tend to understand about light in a aquarium

  6. I TOTALLY agree with this. I HATE seeing picture-perfect scapes on Instagram that are lit brighter than a supernova! They are only lit that way for clarity of photos but newcomers to the hoppy are misguided into thinking that brighter is better!
    I personally have a 50l setup that’s CO2 infused and fed with liquid and substrate ferts. It has LOW lighting and the combo of ferts, CO2 and lighting give perfect, medium growth and minimal algae!

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