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The biggest threat to the natural wicking action which keeps plants in your WaterMizer GrowTainers properly watered at all times is letting the potting MIX get too dry. This brings the natural wicking action to a screaching halt and it's just a chance I don't want to take. It's far too much trouble to restore the wicking action, so why not make sure it isn't lost in the first place?

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I call this solution The FillTainer and it's based on a simple and reliable law of physics. Take two glasses and fill them both about half full. Run a tube -- also filled with water (no air) -- between those two glasses with both ends of the tube kept underwater at all times. If you set one glass up on a book, you'll notice water will run into the "lower" glass until the water level is exactly the same in both glasses. If you take that same glass off the book and put it back down on the table, water will flow from the fuller glass until the water level in both glasses is the same again.

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So the idea is that our GrowTainer is one of the glasses and our FillTainer is the other one. A 3/8" O.D. clear vinyl tube is run between the two containers. As long as the tube is kept filled with water, and as long as both ends are under water in their respective containers, the fuller container will flow into the less full container until the water level in both containers is exactly the same. As a practical matter, I've learned that it's impossible to fill this tube AND get both ends where they need to be withOUT ending up with a bubble at the highest part of the clear vinyl tube. My *theory* so far is that as long as the air bubble doesn't occupy the full inside diameter of the tube, water will still continue to flow past it in either direction -- as needed -- to keep the water levels in both containers at exactly the same level. Unfortunately, the clear tube also allows algae growth, but we NEED to be able to SEE to make sure the air bubble doesn't get too big. If it does get too big, it's a simple matter to re-prime the tube to let the air out. The best way to accomplish this is with the end of a running garden hose held up to the submerged end of the siphon tube in the FillTainer. Use your hand as a 'coupling' between the two loose ends and the surge of water will move the air bubble into the GrowTainer reservoir and restore the siphon action. A wooden 'dipstick' with a measured mark on it can be used to confirm WHEN siphon action is lost -- it's a simple enough thing to check every two or three days.

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One can extend this balancing act to any number of containers which are all on the same level. As the plants take up water through their roots, the water level in the GrowTainer reservoir drops, and water flows from the FillTainer to the GrowTainer -- incrementally and automatically -- so the water level inside the GrowTainer reservoir really never changes enough that you could see it. All that makes the FillTainer unique is it has a float valve (a $4.56 part which is commonly used on evaporative coolers -- a.k.a. *swamp* coolers). The float valve is connected to a garden hose bibb with a 1/4" white vinyl tube. The float valve is adjusted to maintain a 'fixed' water level inside the FillTainer. Rain can cause the FillTainer to 'overfill' slightly -- about 1/2" -- but this added water flows into the GrowTainers too. Once the level rises about 1/2" above the 'fixed' water level, the excess flows out the overflow holes in the GrowTainers.

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The FillTainer is made from a $6.47 tote from Lowe's. Measure up 6-1/2" to a centerpoint and drill a 3/8" hole through one short end of the container. The float valve is installed through this hole. As this location is above the level at which any excess flows out the overflow holes in the GrowTainers, it doesn't have to be perfectly water tight, just secure. The fiber washer goes up against the inside wall of the tote; the little nut tightens up against the outside wall -- tighten up snug with pliers or a wrench. The water level in the GrowTainers is 3-1/2" deep BUT there is 2" of wood underneath, so measure up inside the FillTainer to make a mark at 5-1/2". Adjust the float valve arm to maintain the water level at that depth. Let's move on to the next step.

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