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2x13w T5 enough for low-tech 180 litre?


1 Mar 2010
USA / London
Tank dimensions are 76cm (L) X 47cm (W) X 53.5cm(H)

Tank comes with 2x13w T5s - dont have much experience with T5s. Planning on growing mosses, ferns, red lotus, anubias, and maybe some ranalisma rostrata in the foreground.

Cheers for the help.
This might help.


I know the old w/g rule is often frowned upon, but I think it's still a good place to start. For T5s around 1w/g is often suggested for a low-energy setup; so you'll need around 40 watts of T5; perhaps slightly less. Personally, I'd go for T8s, around 1.5 w/g - 60 watts. Either way aim for a 6-8 hrs photoperiod.
Actually the real problem you have and will find, is which tubes will fit over your tank and can get suitable waterproof control gear for.

From here T5 are available in 549mm @ 14W and 24W.

Arcadia to a waterproof ballast for 549mm @ 24W.
The 24W daylight is only £2.74.

You might be able to squeeze a Juwel length tube @ 35W and 742mm if you want more light (and more expensive typical Arcadia Juwel length tube being £15 odd).
The above Arcadia drivers work with these Juwel tubes as well.

I have two of these 35W Juwel tubes over my 180litres, this is high light and high tech and high watching in case it all goes wrong. At present it is fine, but ran for two years 2 x T8 @ 25W each no issues.

So plenty of choices. I would start tank running low light and move up in lumens as you progress.
I have one 30watt T8 bulb over a 180 litre low tech discus tank, probably the same dimensions as yours. 10-12 hours a day.The light is a couple of cm's above the water line.

The plants I have in there that grow are; hygrophila siamensis, crypt parva, bacopa sp. ludwigia repens, anubias nana. I am sure I could grow most of the easy plants. I tried hygrophila pinnatifida a few weeks back but that dissapeared in a few days, a rotala species also really struggled. Half way up the tank I have weeping moss and fissidens holding their own, very, very little growth though. I couldnt get java moss to grow on coconut on the substrate. I will put a pic up later.

I reckon your 3x13 bulbs will probably throw out more light than mine so I reckon you would be fine for the easy plants. It will be fun for you learn which ones need more light too and move them around to see how each responds to more or less light.
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I think im near the limit of plants mass without co2 because the lower leaves of the bacopa were falling off. Im not definite about that though, just a guess. Maybe light? dunno...

Oh yeah and there is vallis and half a dozen bucephalandra in too.

not bad for 1/6 watt per litre!

(apologies for the shocking scratches on the tank)
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T5 are more efficient than T8 and considerably cheaper than LED for the same lumen output.

However LEDs may be cheaper to run in the long run, especially if you take into account say 2 year T5 tube life.
Thanks for all the replies. There was a tank I had my eye on with that particular light set-up. Is retrotiffing a canopy relatively straightforward? I have never done so in the UK - might go LED's just for coolness factor and electricity in that case. Cheers!
A few thoughts... Why not get rid of the canopy altogether and use either an LED unit on braces over the tankmor have a led or T5 unit suspended over the tank? Plenty of options for led nowadays and really not that much more than T5's especially chinese led units which are getting very good nowadays.
Lighting is changing quickly, metal halides have been almost universally superceded by leds now, and T5's and T8's are next in line for the has been pile of tech.

Why not just use the light that comes with the tank and forget about everything else?
As shown in the chart and as discussed in the thread link in post #4, T5 will produce significantly more light than a T8 and will be sufficient for low tech.
Anubias, mosses and ferns require very little PAR energy. Growth will be slower than if you blasted the tank with tons of light, but so what, it's low tech right?

metal halides have been almost universally superceded by leds now
I only wish the LED market would be more clear/reasonable. Right now i feel the manufacturers are over pricing evrything because it's new and people can't realy gauge the value of a light. It will probably get better soonish, but right now someone can have something crafted in Asia cheap and sell it fo ridiculous prices here, while a good for value one can't realy be distinguished that easy. And there are a lot more manufacturers compared with say T8/T5 units or even metalhalide.