One of the beauties of a low light tank, is that the equipment demands are very low.
Everything can be purchased at even the worst of pet stores, and for a relatively low price.
Here is the list for the 15 gallon:
A hang on the back filter, in this case, an Aquaclear 30,
A cheapo powerhead (aquarist term for submersible pump used for water movement),
A submersible heater, in this case a 100 watt marineland visi-therm stealth,
and a home made lighting fixture with 2x15 watt fluorescent bulbs.
The set up of powerhead and heater:
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The lighting fixture was assembled using the end caps and ballasts ripped from $8 fixtures from Home Depot. In addition, reflectors from the local weed grower store were added. The bulbs were upgraded to a more plant friendly full spectrum bulb. It is important to shield the ballasts to avoid unnecessary replacements and a smoky house.
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That's it. Nothing more than filter, heater, water movement and a bit of light!