How Do You Work Out What Lighting You Need?

[Naringlo]

I was just thinking about how you go about working out what lighting you need. I'm sure there are a lot of factors like fert dosing, what plants (high and low light, dimensions of your tank etc.
 
Is there a general rule or sum you can follow?
 
Well any sort of explanation would be great.
 
Thanks for reading.

 

[frapadoodle]

The easiest is watts per gallon.
Ie in my 10 gal. I have two ten watt bulbs for twenty watts. Divide that by the ten gal. of the tank and you have two watts per gallon.
But as you say other factors are involved. My 55gal. is a deeper tank, so tbe watts per gal. at the surface won't be the same at the substrate.
And the plants and planting also are a factor, as well as tannins in the water, height of the light fixture from the tank.
And photoperiod also plays a factor.

 

[Naringlo]

Is two watts per gallon considered high lighting? In smaller tanks. I don't actually know much about this rule.
 
Thanks for you help.

 

[frapadoodle]

Depends on plants. How much light they need, how heavily planted.
For mine, yeah it's high. Water is clear, small tank area, sand substrate. So lot's of reflection.
Not heavily enough planted yet so a weekly algae scrub.
Have not upgraded the lights on the 55gal. yet so still at 1 watt per gallon. I have a photoperiod of 12 hours on that tank and no algae.
But also no high light plants yet either.

 

[Naringlo]

There seems to be a lot to it! Though I'm still keen to gain the knowledge.
 
I asked the planted mod about my plans. A 30L, he said 18w. I didn't mention my plants or what I'd be dosing though, but doing the watt per gallon, it comes out all good.
 
30L, daily dose of Neutro+ ferts, Neutro Co2 liquid.
Cardamime lyrata, Lymnophila aromatica, Moss Ball, Rotala rotundifolia, Taxiphyllum spiky, Pistia stratiotes, Java moss, and hairgrass. Forgot the proper name. 400L per hour rated filter, Tropica substrate topped with caribsea complete substrate, to keep the brown look. 
 
The lighting choice is 18w and 24w. I will personally go for 18w because I don't want to cause lots of problems. Unless one of the plants is high light, I guess I may need 3 watts per gallon so 8 gallon to 24w.
 
I tried looking into kelvin thing but the explanations I found went on a bit and didn't explain much of the point.

 

[Ps3Steveo]

The 18W will grow anything.

 

[Naringlo]

I don't doubt your word. Just trying to figure it all out. e.g. using the watt per gallon method, but that's not right. Trying to understand kelvin, spectrum, isn't going in to my head.
 
Didn't you grow plants in your Arc with the light that comes with it? Like a 9w?
 
Anyway, you two are pretty knowledgeable, how do you know so much? Is it experience, common sense on lighting, a book, or even just random research and readings?

 

[frapadoodle]

For me reaserch, gotta love the interweb. Advice given here and a couple of planted sites, and trial and error.
I haven't gone the co2 route yet. And Flourush is my fert once a week.
Nothing fancy, but my plants are happy.

 

[levahe]

Lighting isn't the most important factor in a planted tank, getting the other factors like co2, ferts and flow right is. You also need to have a good maintainance schedule to go with it. Honestly don't get too hung up on the lighting like wpg or which k to get. As long as the lights arent too dim or too bright they will be OK and as for kelvin its purely cosmetic and won't affect plant growth.

Basically you can grow pretty much any plant with any lighting , higher lighting will mean that your plants will grow faster and demand more co2 and nutrients.

 

[Naringlo]

Oh right nice, a simple set up I take it? What plants you growing?
 
So basically, just have a good balance, with nothing being too under powered or over powered with trial and test? 
 
I'm just going to have to go for it and use common sense xD

 

[Lunar Jetman]

Lighting isn't the most important factor in a planted tank, getting the other factors like co2, ferts and flow right is. You also need to have a good maintainance schedule to go with it. Honestly don't get too hung up on the lighting like wpg or which k to get. As long as the lights arent too dim or too bright they will be OK and as for kelvin its purely cosmetic and won't affect plant growth.
Basically you can grow pretty much any plant with any lighting , higher lighting will mean that your plants will grow faster and demand more co2 and nutrients.

This! Get flow and ferts right and you don't have to worry about lighting. What lights do you currently have?

 

[Naringlo]

I don't even have the tank yet. Getting it sometime this week. I will be buying an 18w. The other option is 24w but most seem to think that will be too high.
 
Going with Neutro Co2 liquid, Neutro + Fertiliser, Should be 300 - 400lph. 32L Long. Tropica substrate topped with Colombo flora base. High to medium requirement plants.

 

[LicianDragon]

This is something I've been trying to work out as well. I have a  20g high tank with two 15w bulbs. I've always been under the impression this is low-barely medium lighting. I dose co2 every mmorning and use eco-complete substrate.  
This whole lighting thing really confuses the heck outta me. Does it really not matter so much how high/low your lighting is? What about high light plants?