If your 23 watt 6500K bulbs are the screw-in CFL bulbs, mounted horizontally above the tank, and have good reflectors, and they are right at the top of the tank, those alone will be giving you good low light, around a PAR 30 to 35 range. But, if they are raised more than 3 inches above the top of the tank, or don't have good reflectors, you probably barely have enough light for the plants.
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Hoppy
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