Description: In-tank surface skimmer/overflow box for sumpless tank. Operated by powerhead. Removes oily film from surface of water and allows for precise water level control on sumpless tanks. Also functions as micro-refugium.

Cost: about $10-$15

Materials needed, in addition to a small powerhead to run the overflow:

1. A lee's overflow box, roughly 7" long, 5" wide, 6" deep (about $10)

2. *A J-tube for a freswater power filter* ($???)

3. *A piece of 1/2" by 3/8" rigid plastic bar (optional), slightly longer than the width of the tank ($???)

4. Some misc. fittings, depending on what powerhead you're using.

*both of these items i happened to have lying around. The J-tube is commonly available from a pet store, but the plastic bar is harder to find. The piece i'm using is a piece of 3/8" thick lexan that was cut with a saw.

5. Tools needed: hacksaw, dremel tool, candle, boxknife.

Make sure have an open area cleared for the specimen box to hang over the tank wall into the tank.

1. Determine the water level you want to maintain in your tank. Once you know what distance you want between the top of the tank rim and the water's surface, subtract about 1/8", and measure this new distance down from the top front edge of the overflow box and draw a line. This will be the depth of the slots you are about to cut into the overflow.

2. Mark off slots or holes if you prefer at even intervals along the front edge of the container, extending from the line you've drawn to the top front edge.

3. With the dremel tool, very carefully cut each slot (or hole) down to the marked line. Be careful, this plastic is very brittle. Holes are easier to work with than slots because they're not as likely to break. See fig. 1.

4. Once you've cut all of the holes, use the boxnife to straighten the edges a little. Light the candle and carefully hover the flame beneath each hole/slot to slightly melt and smooth over the rough edges.

5. wash the overflow box. Test-fit it on the tank to determine if the holes are the right depth. The overflow box will not sit completely vertical; the inside top edge should rest about 1/4" or more lower than the outside. The box should be aligned so that the bottom inside edge and the top inside edge both rest on the aquarium.** The water will not flow into the overflow along the bottom of the slots, rather it will be about 3/16" higher (depending again on your powerhead), cancelling out some of the difference due to the overflow's tilt. See fig. 2. Cut the holes larger if necessary.

**If you choose to use the plastic rod, it should be aligned so that the bottom inside edge and the top outside edge both rest on the aquarium.

6. After you're satisfied with the slots/holes in the overflow, place the J-tube so that the short end is near the bottom of the inside of the overflow and the long end is hanging into what would be the tank. The powerhead should be positioned so that the intake is attached to the long end of the j-tube***. If you so desire, put the powerhead's intake screen over the end of the tube that sits in the overflow to prevent it from sucking up large particles. The powerhead can be stuck via suction cups either to the outside of the overflow box or to the tank's wall. It may be necessary to cut the long end of the J-tube shorter to make the powerhead fit. See fig. 3.

***How you attach the J-tube and powerhead intake will differ depending on your choice of powerhead. Plastic elbow fittings or clear plastic tubing work best, both are available at home depot.

7. Wash everything and place the overflow system into the tank. Suction-cup the powerhead to the tank wall if necessary. If you were to plug in the powerhead at this time you'll quickly notice that the overflow box floats upward off of the tank edge as the water level inside drops. One solution for this is to wedge a thick pencil or wooden rod between the outside rim of the tank and the box's overhang, this will wedge the box in place so it can't move. The drawback to this is that the pencil tends to fall out, and if you're using a float-switch topoff system this can be disasterous. A more permanent solution uses the 3/8" by 1/2" plastic bar. Use a hacksaw to cut the the bar so that it fits perfectly between the front & back of the tank's glass. Use a dremel tool to cut notches in the bar so that it fits over the overflow box's outer edge but under the rim of the tank, wedging the box in place. See fig. 4.

8. Cross your fingers and plug in the powerhead. Ideally, the water should drop about halfway then remain stable. If the box sucks dry completely, add a little more water to the tank and try again. If the water level doesn't drop, remove water and try again.

9. Over the course of a day the water level in the overflow box will vary due to evaporation, but the water level in the main tank should remain constant. Kalk/topoff can be dosed via a float switch in the overflow.



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