# Lighting for aquarium plants

I have a 27 watt led light fixture for my aquarium, but I need at least 54 watts in my aquarium for plants I want. Would adding another led fixture that is the same as the first one increase the wattage amount?

GlennO
How do you know that you need 54 watts? The wattage will double but that’s not the same as doubling the PAR level although it will likely be close where the lighting overlaps fully.

How do you know that you need 54 watts? The wattage will double but that’s not the same as doubling the PAR level although it will likely be close where the lighting overlaps fully.
medium light = 0.5 watts per liter, 1 gallon = 3.785 liters, 3.785 liters times 29 gallons roughly equals 110 watts, 110 liters x 0.5 watts equals 55 watts. If I include substrate, which roughly would take up around two gallons of space, that's 27 gallons times 3.785 = 102, multiply that by 0.5 equals 51 watts. Most of my plants in there will need medium to high light when I plant them, so I wanted to double the wattage. Would that work or would I need an entirely new light fixture? Also, feel free to correct my math if I'm wrong on anything, still learning about aquarium plants and would love to know if I'm wrong.

GlennO
I think that the medium light example of 0.5 watts per liter might be for T5 fluorescent tubes not LED. For example a 36 inch Fluval Plant 3.0 is 46 watts and these can grow relatively demanding plants (depending on depth).

Also if you're aiming for medium to high light to grow some more demanding plants you'll need to be injecting CO2 or else you'll have an algae farm (sorry if you're already aware of this).

Mudminnow
medium light = 0.5 watts per liter, 1 gallon = 3.785 liters, 3.785 liters times 29 gallons roughly equals 110 watts, 110 liters x 0.5 watts equals 55 watts. If I include substrate, which roughly would take up around two gallons of space, that's 27 gallons times 3.785 = 102, multiply that by 0.5 equals 51 watts. Most of my plants in there will need medium to high light when I plant them, so I wanted to double the wattage. Would that work or would I need an entirely new light fixture? Also, feel free to correct my math if I'm wrong on anything, still learning about aquarium plants and would love to know if I'm wrong.
Welcome to Fishlore.

Watts/liter or watts/gallon was used as a rough estimate for lighting back when everyone was using T12s. But, then we started using T8s, T5s, and now LEDs. LED lights crank out much more light per watt than their older counterparts. Plus, they're often adjustable. Therefore, the old watts/unit volume isn't very useful anymore.

My recommendation is to buy an adjustable output LED light that is designed for plants and fits the size of your tank. Personally, over a 29 gallon, I'd recommend the Finnex Planted 24/7 LED light, because that's one that I've had success with. But, there are many lights out there to choose from.

dcutl002
shad000 can you tell us what light that you currently have? I’ll see if I can dig up the PAR value for it. Secondly, what size tank? 29 gallon?

TClare
Also you can use lumens per litre as a guide, since lumens are usually given in light specifications, but PAR often is not. Roughly low light plants need 10-20 lumens per litre, plant with high light requirements need over 40 and those with medium light requirements in between. I just use ordinary led floodlights, from 10 - 50W depending on aquarium size and light requirements of the plants.

86 ssinit
Yes the watts/gallons was for fluorescent lights. LEDs have changed that. Where the old fluorescent lights cost a fortune and were huge with fans in them LEDs are much smaller and lighter and run cooler. Yes LEDs are much cheaper too and run much cheaper. Some led lighting comes fully adjustable some 24/7. Plants grow much better. So many different companies making led lights. Some are very expensive I’ve got \$40 vivagrow 24/7 leds that are over five years old and still working great. No changing bulbs every 6 months with leds.

86 ssinit
That light should be fine. Looks like a fully programable light. Nice! I’ve got a hygger that is similar and works great.

MrMuggles
Also if you're aiming for medium to high light to grow some more demanding plants you'll need to be injecting CO2 or else you'll have an algae farm (sorry if you're already aware of this).
this is indeed really important. doing co2 up front is worth it, don't wait until the algae takes control or it will take even longer to even things out.

In regards of C02, can anyone recommend a good C02 kit that's pretty cheap, but good for a 29 gallon tank? I thought about also just using API Carbon Booster, but I'm unsure about the whole "liquid carbon" thing.

Mudminnow
In regards of C02, can anyone recommend a good C02 kit that's pretty cheap, but good for a 29 gallon tank? I thought about also just using API Carbon Booster, but I'm unsure about the whole "liquid carbon" thing.
You could start a whole new thread on CO2. But, before you take the plunge, do a bit of research. Its use has pluses and minuses.

Pluses of CO2 use:
• You can grow any type of plant.
• Plants grow faster and fuller.
• Can use higher (or lower) light levels
Minuses of CO2 use:
• Higher cost
• Takes practice to get right
• Increased tank maintenance
But, to answer your question. I've found the FZONE Mini V3.0 Dual Stage to be a pretty good "budget" option. You can get less expensive regulators, but they are typically not dual stage. And, dual stage is really the way to go for aquarium CO2 regulators--no CO2 dump when the tank's nearly empty.

86 ssinit
I don’t think you need co2. I never recommend it. You’ve read the pluses but there are more minuses. The fluctuating ph may kill your fish or stress them. A problem with the co2 amount will kill your fish. I’ve never used it. Just not worth the risk. It’s a tool professional plant keepers use. Yes it costs money. The system is expensive and co2 is needed monthly. I’ve grown many plants without it. I’ve used the api co2 booster. It’s got no co2 and is an algeacide. It kill algae. Also costs money and needs to be added daily in the morning to work correctly.

Mudminnow
...A problem with the co2 amount will kill your fish....
Not to mention, fluctuating CO2 also stresses your plants and encourages algae growth.

I myself use CO2 in most of my planted tanks, because I love the results I get with it. But, the point is well made. It's not for everyone.

GlennO
I don’t find the cost of CO2 to be that much of a factor. A decent regulator can be bought for less than what many people spend on a filter and I spend maybe \$80 per year on gas. The biggest drawback for me is that I don’t always feel like spending the time doing the maintenance (plant trimming etc) required to keep it looking good. Plants grow so much faster. You have to be a keen underwater gardener!

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