This is pretty cool video. In your case, you could probably gut the existing fluorescent hardware and reuse the canopies with single LED
tubes as described in the video. Not sure if two tubes would fit in your canopies.
Or do a single rain gutter along the span of the tank.
Vivagrow makes a 48" Finnex 24/7 knockoff for about $65. Dimmable, color control, 24/7 mode. It MIGHT work with your setup. Probably more light than you need. But it is dimmable.
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