Watts Per Gallon/litre - Any Help?

[Jayladd]

Hello,
I have a new tank measuring:

Length: 48"
Width: 12"
Height: 15"

I think that works out as 134 Litres or 29 UK gallons.

I want some simple, low tech plants to go into my aquarium. I only have plain aquarium sand in my tank. Should I really have a special substrate?
Anyway, back to my main question, is there a general rule to how many watts per litre you should have to be able to grow most plants?

I have seen a 42" T8 bulb at 40 watts - Would this be enough or would I need to buy two?

Any suggestions on easy to care for plants would also be a great help. (That don't need co2 injection)

Thank you for your help and time.

 

[Lufbramatt]

Id get 2 t8 tubes or one t5 high output tube. In my 29gal I grew java fern and vallis in play sand with no co2 or ferts and they grew lots, not as quick as a high tech setup obviously but looked nice and healthy. Anubias should do well too.

 

[minnnt]

1 would be fine imo to grow basic low tech plants.

 

[Lufbramatt]

Yeah that tank is shallower than mine so one would probably be ok.

 

[Jayladd]

Thanks for the replies guys.

What would you classify as basic plants minnnt?

 

[FishFanatic04]

I grow anubis in my 46g with the lights that came with the tank so that's one for sure.

 

[minnnt]

Thanks for the replies guys.

What would you classify as basic plants minnnt?

Anubias
Cabomba
Cryptocoryne
Elodea
Hygrophila
Java Fern
Limnophila
Moss

All of the above should grow under one T8.

Bulk your aquarium out with Crypts, Java Ferns and mosses and you will be laughing mate. Very simple to grow indeed.

 

[Jayladd]

One T8 bulb will only give me 1.37 watts per gallon, isn't that a bit too low? Would it be preferable to get two or will i get too much algae?

Thanks again

 

[OldMan47]

A 4 foot long t-8 fixture is plenty for low light plants in that tank. A twin bulb 4 foot long fixture would let you grow medium light plants at a bit over 2 WPG. Figure that you are looking at 8 watts per foot on a T-8 and 10 watts per foot on a T-12. The only thing that varies in those sizes is the spectrum, the wattage is standardized.

 

[waterdrop]

At the inch dimensions you've given, our TFF calculator gives us figures of 142L or 37 US gallons. Low light technique works very well when working closely around 1 watt/USgallon (In addition to plenty of our planted experts writing documents about this I can attest that I've had plenty of low-light technique success in a tank with light at 1.07 W/USG.)

Using OM47's 8w/foot your 4F T-8 would be running at 32W which would put you at .86 w/usg or if it's really 40W then that puts it at 1.08 w/usg. None of that matters - all of it is close enough around 1 w/usg to do a fine job. The actual light will diminish with time anyway and you'll be better off using a fresh tube each year or two since you're down around the low side of low-light.

What you probably don't want to do is to get your light up around 2 w/usg because that would be "putting the pedal to the metal" and pushing plant growth too much. Why? Because with a low-tech tank you wouldn't be supplying enough carbon (C) for the plants to build all those carbon-backboned sugar chains. 2 watts of light (or above) would make them cry out for food and the way they make food for their cells is with lots and lots of carbon coming from lots and lots of CO2.

Plants on land have access to lots and lots of CO2. Submerged plants don't. This is why there is such a thing as "high-tech" planted tanks where there is lots of gear to maximize the CO2 for the plants without going too high and killing the fish.

1 w/g, java ferns, swords and the others mentioned.. that's the ticket.

~~waterdrop~~
ps. agree with OM47's comments and some of the others up there

 

[minnnt]

Don't rely too much on WPG. It's good for a guide, but the plants i listed will adapt to what ever light they are given and grow accordingly. A member on here used to have a fully planted tank and didn't even have a light other than natural light.

Check out Llj's tank... Grown at just 0.77wpg of light.

Exactly the reason why you shouldn't get too ate up with all the WPG figures...

Here is her full journal.

 

[ian]

i'll also just add for simplicity reasons...

Low light - slow growth

Higher light - fast growth (C02 and extra N and P needed to support the plants fast growth)

there are other important factors when growing plants IE Good flow, ensuring you're getting even distribution of water around all plants.

 

[Jayladd]

Thanks for the advice everyone! I'll just stick to the one t8 bulb.

Anyone use a T8 Aqua-glo bulb?

 

[minnnt]

I have the T5 Aqua Glow. It's nice, but i prefer a lesser kelvin bulb. Something around 5000k.

 

[Jayladd]

What is Kelvin again? Sorry I'm probably being really stupid haha