Retrofit of an Aqua One 620 with LEDs - The Planted Tank Forum
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post #1 of 2 (permalink) Old 07-15-2012, 08:48 AM Thread Starter
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Retrofit of an Aqua One 620 with LEDs

i ran my 620 for a number of years as a reef tank. after having to strip it down when the carpet was replaced, and having to deal with sorting the rust on the metal plate and replacing a rusty ballast, i decided to go fresh water. now, the tank with the hood and filtration system is a neat and tidy package, but after replacing the blue/white tubes with the stock red/white tubes, the lighting struck me as disappointing. below is what the standard light fitting looks like:

i'd noticed that LEDs seem to be all the rage now, and after reading hoppy's thread after a fashion, and inspired by fizzout's thread, i decided to have a crack at retrofitting the 620's hood. i started out by ordering 2 x meanwell eln-60-27d dimmable drivers, 8 cree xm-l cool whites and 8 xm-l neutral whites.

there's no room in the hood for the drivers, so i mounted them in the cupboard:

according to the vendor, the drivers can be happy with 6-8ft of cable between them and the LED array. the local electronics supply chain had 4 wire audio cable with 18g wire which happily allowed me to use a single cable per driver carrying the led power and power for the dimmer. i probably could have put the dimmers in the cupboard, but i prefer to have them in the hood. i cut a couple of holes in the top of the hood and mounted 80mm quite case fans:

i used 2 x18 inch long heat sinks which i tapped to screw the LEDs to. not sure the exact spread, but close to 2 1/4 inch apart. in order to get clearance for the heat sinks, and to get the lighting further down so that the sides of the lighting section didn't interfere with the light spread, i had to add extensions to the mounting posts. these posts are a bit fragile, so i had to be careful to drill the original holes larger to take the bigger thread of the extensions. once all was screwed down i cut some 3mm perspex for a splash guard. i tried to bond the heat sinks to the aluminium base plate with thermal epoxy, but the claims of permanency by the manufacturer seemed somewhat exaggerated, and gave way when i started drilling, so i used strips of aluminum screwed to the heat sinks to hold them in place.

although everything seemed to be running cool, i noticed that the water level seemed to drop faster. i suspect this may have been due to the fans, so while i trimmed the splash guard so the hood fitted correctly, i fitted some thin closed cell foam to reduce the airflow coming from the tank.

prior to fitting, i tested the lights and left a a connection from each string open so i could shove an ammeter in line and mark off where 1a, 1.5a and 2a were on the dials. if i picked up nothing else from hoppy's thread, it was to expect brightness, so i wore my lcd welding mask before flicking the switch

i never had quite comprehended till that moment just how thermonuclear those xm-l's are. at the moment, i'm running them at 1 amp. i don't have a par meter, so i have no idea if i'm getting spectrum, but in terms of intensity at least, a vast improvement over standard.

the top picture is the standard lighting, the bottom, the new lighting taken with the same aperture and shutter speed from the same distance. the over exposure gives you an idea of the brightness difference, but i don't know if the plants will appreciate it. the tank is 2ft x 14inch and distance from lights to substrate is 14 1/2 inch. i do have 80deg optics, but for the moment i've left them without those lenses. due to the filter and front access, the light section is restricted to a roughly 5 1/4 inch wide strip down the centre.
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post #2 of 2 (permalink) Old 07-15-2012, 11:45 AM Thread Starter
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yegads! i hadn't noticed hoppy's other thread that wasn't sticky. filled out the numbers in the 5th version of his spreadsheet, and assuming i didn't stuff up, it comes out at 132 par (that's using the suggested 70deg for bare led rather than the 125 the data sheet says). apparently i should be driving them at less than 1/2 amp.
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