After losing my last fish from 20G (2 foot tank) and blacking the tank out for six months to kill off the Caulerpa taxifolia (now illegal in New South Wales), I decided I would convert the tank for keeping corals. The tank had already been up an running for over 4 years, had an established DSB and live rock. All it really needed was an upgrade to the lighting (plus skimmer and auto top-off).

For the lighting, I had a choice between 150W metal halide (DE Shoplighter) or going with T5. As I already had the metal halide fitting, that was going to be the cheapest and quickest option, however, I felt I might actually have too much light and at the very least, more light than the corals needed. I also wanted to give T5 lighting a go so I can offer more informed comments. Given that T5 lamps put out at least 50% more light than normal output T8 lamps of the same form factor and that I had a number of corals growing well under 4 normal output fluorescent lamps in a tank that is deeper than 20G, I figured that four T5 lamps would be sufficient for all the corals I wanted to keep: various Acropora spp., pocilloporids, Hydnophora and miscellaneous other genera.

Components

Lighting Components

Table 1 lists the components purchased for the lighting upgrade.

Table 1: Components used for the lighting upgrade

Component	Cost	Place of purchase	Part number
Total	$367.41
2 Atco PC 2/24 T5 Pro Ballasts	$154.00	John R Turk	ATCO 22085182
4 pairs of AAG Stucchi Weatherproof T5 Lampholders	$36.00	Litoria Pty Limited	1783-G5/16
4 pairs of IceCap T5 Lampholder mounting bases	$26.80	Litoria Pty Limited
2 aquaz 54W Spider Paraobolic Reflectors	$76.48	Reef Culture	T5PAR54
8 T5 Clips	$3.52	John R Turk	LIGST036
2 Osram T5 FHO 24W 6500K tubes	$33.00	John R Turk	FQ 24W/865
1 aquaz T5 FHO 24W 10000K tube	$17.94	Reef Culture	T510K24
1 aquaz T5 FHO 24W Actinic tube	$19.67	Reef Culture	T5ACT24

Other Hardware

Completed hood

Figure 1: The inside of the hood showing endcaps, tubes and reflectors.

Figure 2: The rear of the hood.

Figure 3: The rear of the hood with the ballasts exposed.

Irradiance Measurements

To determine how much light I was getting from the T5 tubes, I used my quantum meter (QMSS-ELEC) made by Apogee Instruments. It is not easy to measure the light from all four tubes as I can't get the probe of the quantum meter in the tank with the hood closed. I decided to measure the irradiance from just two of the tubes and assume that the total irradiance would be approximately double with all 4 tubes switched on.

I placed the probe of the quantum meter

Last updated: January 11, 2006