Advice on T5 bulbs for a 3 foot tank

[Stu]

Hi all,
I'm thinking of upgrading my lighting from T8 to T5 HO.

My tank is 3 foot long x 15 inches high x 12 inches deep (80 litres) and currently running 2x 25W T8 bulbs in my custom built hood.
I'm looking at 39W T5 HO bulbs as I believe these will fit in my hood ok(?).

My question is should I go for just 2 39W bulbs (78W total) or go for 4 bulbs (156W total)?
Years ago I used to run 150W of power compacts on the tank and it seemed too much light as I had problems with algae, but are High Output T5's different in intensity?
I often see complete 90cm/100cm luminaires for sale with 4x 39W bulbs in them so this is what has made me question if 4 is better.

At the moment I have Crypts, Anubias nana, HC 'cuba', Flame Moss & Java Fern in the tank but will be adding more plants in future. My main concern is to get enough light to make the HC carpet the foreground.

I am running pressurised CO2 at 25-30ppm, 11hr photoperiod, dosing macros once a week and micros 3 times a week.

 

[mlgt]

Ive just bought a starter unit myself and at £30 for 2x39W T5 unit + £8 for 2 lights its a cheap upgrade.

I have an older Juwel 180l tank with the T8's. So I will have 138W in total once I get my co2 installed.

If you have the space go for more, means you have to find a balance for the tank.

 

[SKP1995]

2x39w is more than enough. My tank has the same base dimensions, but with a little more height and I use 2x39w which has allowed me to grow pretty much anything. 4x39W would just be overkill.

 

[ceg4048]

...My question is should I go for just 2 39W bulbs (78W total) or go for 4 bulbs (156W total)?
Years ago I used to run 150W of power compacts on the tank and it seemed too much light as I had problems with algae, but are High Output T5's different in intensity?
I often see complete 90cm/100cm luminaires for sale with 4x 39W bulbs in them so this is what has made me question if 4 is better.

DANGER Will Robinson! 160W of T5 over a 30USG tank without paying careful attention to CO2/nutrient will have similar effects as the thermonuclear meltdown at Chernobyl. T5 produce more photonic energy than T8, possibly by 50% or higher. Efficient reflectors will magnify this effect even more. What happened years ago with those power compacts was no fluke and I've heard tell that the long T5 tubes distribute even more energy that the PC's.

At the moment I have Crypts, Anubias nana, HC 'cuba', Flame Moss & Java Fern in the tank but will be adding more plants in future. My main concern is to get enough light to make the HC carpet the foreground..

HC does not require high light to perform it's carpeting magic. What HC requires to perform this trick is high CO2.

I am running pressurised CO2 at 25-30ppm, 11hr photoperiod, dosing macros once a week and micros 3 times a week.

I'd suggest that you get a pot or two of HC and try growing it with what you have. Tweak CO2 and flow and see how it goes. I would look to improve flow rate and CO2 before increasing the light.

Going for megawatt lighting for aesthetic appeal is one thing, but thinking that HC or any plant needs that level of lighting is just asking for trouble.

Cheers,

 

[Stu]

Thanks for the opinions guys.

I didn't want to be continuously 'tinkering' with the tank and to be scared of leaving it for a day or two, so I'll go for the 2 bulbs!

I have HC growing under the current conditions (planted late January, CO2 added late February) and it is starting to spread but not very fast.
I believe my level of flow is good but I'll increase the CO2 a little and notice the changes.

Thanks again