Lighting is the one piece of aquarium equipment people most often get wrong in both directions \u2014 too weak for the plants they want, or so strong it triggers an algae problem they spend months fighting. Getting the light right from the start makes a planted tank dramatically easier to keep.<\/p>\n
Light is the energy source for photosynthesis. Plants use it, along with CO2 and nutrients, to grow. The catch is that all three have to be in balance: if you give plants more light than they can use \u2014 because CO2 or nutrients are the limiting factor \u2014 the surplus energy doesn’t vanish. Algae, which is far less fussy about conditions, uses it instead.<\/p>\n
This is why “just add more light” is such common bad advice. More light only helps if the plants can actually keep up with it. Below their limit, extra light does nothing useful and often does real harm.<\/p>\n
You don’t need to measure PAR or memorise lumen charts to succeed. What matters is which of two broad categories your setup falls into.<\/p>\n
A modest fixture, run 6\u20138 hours a day, no CO2 injection. This supports a large and genuinely beautiful range of plants \u2014 Anubias, Java fern, Bucephalandra, Cryptocoryne, mosses, Vallisneria, many stem plants \u2014 and it’s the setup we recommend for almost every beginner. Growth is slower, which also means less pruning and less algae. Our low-tech plants guide<\/a> covers the full list.<\/p>\n A strong fixture combined with<\/em> pressurised CO2 and a full fertiliser routine. This is what you need for a lawn of Monte Carlo, vivid red plants, or a competition-style aquascape that grows in fast. It’s more rewarding to look at and more work to run \u2014 the balance is tighter, and mistakes show up as algae within days. Only step up to this once you’re comfortable maintaining the basics.<\/p>\n <\/p>\n Beyond output, a few practical points decide whether a light works well for your tank:<\/p>\n Plants photosynthesise across a broad range of the spectrum, so any decent full-spectrum white LED will grow them. Where colour matters most is appearance: a warm, high-CRI white makes greens look natural and fish colours pop, while RGB and WRGB fixtures let you push reds and blues to make red plants and certain fish look more vivid.<\/p>\n A common mistake is running a heavily blue-shifted “marine” light on a freshwater planted tank. It looks dramatic but makes plants and most community fish look washed-out and grey. Stick with a white-dominant spectrum for freshwater.<\/p>\n For most planted tanks, 6\u20138 hours a day is the sweet spot. Longer photoperiods don’t grow plants faster once their daily needs are met \u2014 they just give algae more hours to work with. A timer that switches the light on and off at the same times every day keeps the tank stable and takes the decision off your plate.<\/p>\n A “siesta” schedule \u2014 lights on for a few hours, off for a few, then on again \u2014 is popular and can help in some tanks, but it’s not essential. A simple single block on a timer works for the large majority of setups.<\/p>\n Think of light as the throttle and CO2 plus nutrients as the fuel. The moment you turn the light up past what your fuel supports, plants stall and algae takes the excess. That’s why upgrading to a stronger light is rarely a standalone decision:<\/p>\n Our CO2 systems guide<\/a> walks through whether you actually need injection, and our algae guide<\/a> covers the fixes when the balance slips.<\/p>\n You rarely need a meter to work out whether your lighting is off. The plants and the glass tell you.<\/p>\n The fix is usually to dim the fixture, shorten the photoperiod, or \u2014 if you want to keep the light where it is \u2014 add CO2 and step up fertiliser dosing so the plants can actually use it.<\/p>\n Here the fix is either a stronger fixture or \u2014 often the smarter move \u2014 swapping the demanding plants for species that are genuinely happy in low light. A thriving low-light tank looks far better than a struggling high-light one.<\/p>\n Healthy new growth in a natural colour, compact form on carpets, red plants showing at least some colour, and glass that only needs a wipe every week or two. Some algae on the hardscape is normal and nothing to chase \u2014 it’s total absence of plant growth or a sudden algae bloom that signals a real problem.<\/p>\n 6\u20138 hours for most planted tanks, ideally on a timer for consistency. Longer photoperiods rarely help plants and usually encourage algae.\n<\/p><\/div>\n No. A modest full-spectrum LED is plenty for Anubias, Java fern, Cryptocoryne, mosses and similar plants. They don’t benefit from a high-output fixture and can actually do worse under one without CO2.\n<\/p><\/div>\n Yes \u2014 this is the single most common cause of algae in an otherwise healthy tank. Light that exceeds what your plants can use (because CO2 or nutrients are limiting) gets used by algae instead.\n<\/p><\/div>\n A white-dominant, full-spectrum light. RGB or WRGB fixtures add control over reds and blues for appearance, but a plain warm white grows plants perfectly well. Avoid heavily blue “marine” spectrums.\n<\/p><\/div>\n Usually, yes. A high-output light without CO2 is the most algae-prone combination there is. If you’re not ready for CO2, stay with a lower-output fixture \u2014 the plants will be healthier.\n<\/p><\/div>\n Low-demand plants will. High-demand plants (carpets, most reds) will grow leggy, lose lower leaves, or melt. Match the plant list to the light you have rather than forcing it.\n<\/p><\/div>\n The best aquarium light is the one that matches your plants and your willingness to dose CO2 and fertiliser \u2014 not the most powerful one on the shelf. For most people that means a modest full-spectrum fixture on a 6\u20138 hour timer, which grows a wide range of plants with very little algae trouble. Step up only when you’re ready to feed the extra light with everything it needs.<\/p>\n Browse our current lighting range to find a fixture sized for your tank, and pair it with the plants, fertiliser, and CO2 that suit the setup you actually want to run.<\/p>\n How to match an aquarium light to your plants \u2014 low light vs high light, spectrum, photoperiod, the light-CO2-nutrient balance, and the signs your light is wrong.<\/p>\n","protected":false},"author":298,"featured_media":44011,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"wpai_generated_summary":"","_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"mts_hero_image_prompt":"","mts_hero_image_alt":"","_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":false},"categories":[890],"tags":[951,1075,872,947,1089,1093,864,1091,870,1095],"class_list":["post-44010","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-equipment-guides","tag-algae-control","tag-aquarium-lighting","tag-aquascaping","tag-equipment-guide","tag-led-aquarium-light","tag-light-spectrum","tag-low-tech-plants","tag-photoperiod","tag-planted-tank","tag-wrgb-light"],"jetpack_sharing_enabled":true,"jetpack_likes_enabled":false,"jetpack-related-posts":[],"jetpack_featured_media_url":"https:\/\/mytankscape.com\/wp-content\/uploads\/2026\/09\/aquarium-lighting-guide-planted-tank-hero.png","_links":{"self":[{"href":"https:\/\/mytankscape.com\/en\/wp-json\/wp\/v2\/posts\/44010","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mytankscape.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mytankscape.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mytankscape.com\/en\/wp-json\/wp\/v2\/users\/298"}],"replies":[{"embeddable":true,"href":"https:\/\/mytankscape.com\/en\/wp-json\/wp\/v2\/comments?post=44010"}],"version-history":[{"count":1,"href":"https:\/\/mytankscape.com\/en\/wp-json\/wp\/v2\/posts\/44010\/revisions"}],"predecessor-version":[{"id":44014,"href":"https:\/\/mytankscape.com\/en\/wp-json\/wp\/v2\/posts\/44010\/revisions\/44014"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/mytankscape.com\/en\/wp-json\/wp\/v2\/media\/44011"}],"wp:attachment":[{"href":"https:\/\/mytankscape.com\/en\/wp-json\/wp\/v2\/media?parent=44010"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mytankscape.com\/en\/wp-json\/wp\/v2\/categories?post=44010"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mytankscape.com\/en\/wp-json\/wp\/v2\/tags?post=44010"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Recommended Products<\/h3>\n
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High-tech \/ high light<\/h3>\n
Recommended Products<\/h3>\n
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Choosing a Fixture<\/h2>\n
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Spectrum and Colour: What to Look For<\/h2>\n
Photoperiod: How Long to Run Your Light<\/h2>\n
The Light\u2013CO2\u2013Nutrient Balance<\/h2>\n
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Recommended Products<\/h3>\n
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Signs Your Light Is Too Strong or Too Weak<\/h2>\n
Signs the light is too strong for your setup<\/h3>\n
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Signs the light is too weak for your plants<\/h3>\n
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Signs the balance is right<\/h3>\n
Common Lighting Mistakes<\/h2>\n
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Frequently Asked Questions<\/h2>\n
How many hours a day should aquarium lights be on?<\/h3>\n
Do low-tech aquarium plants need a special light?<\/h3>\n
Can too much light cause algae?<\/h3>\n
What light colour is best for a freshwater planted tank?<\/h3>\n
Do I need CO2 if I buy a stronger light?<\/h3>\n
Will my plants survive if my light isn’t strong enough?<\/h3>\n
Conclusion<\/h2>\n
Recommended Products<\/h2>\n
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Internal Link Map<\/h2>\n
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Related Articles<\/h2>\n
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