Hi banana! The Infinity Edge has a suction pipe in the bottom that draws the water out and into the pool. At that point, the water runs through the pool filter. It would need to be manually skimmed, though, for the stuff that may float on top. That's really not a big deal, although it may depend on how much debris you get in it from existing trees, etc. We don't have any large trees that shed around the trough, so it has remained very clean (well, at least for the whole two days we've had it! lol). When you're swimming in the pool, you can't see into the trough - unless you swim right up to the edge, pull yourself up and look down into the trough. I'm not sure if one could be added to an existing pool. The structure was all tied in together when we built it. The steel, the plumbing and the foundation were all done at the same time. To add it in would probably require tearing down and rebuilding the wall on the side where you want the Infinity edge. This is just a guess, though. The cost? Hmmm, that would probably vary widely between builders. Our whole pool cost was about 80,000.00, but that was before our PB left us high and dry. We hope to recover the additional money it cost us to finish it. The other big factor for cost is how long you want the Infinity Edge to be. I guess the usual length is about 12' (I didn't know that until recently). I designed ours to have 45' of negative edge - guess that explains the looks on the PB's faces when I gave them the drawing for our initial estimates!! I just thought, "Hey - if they're going to build a pool wall ANYWAY, let's just have it disappear over the edge :)." Some of the PB's on this forum can probably answer the cost question better than I can. With the slow economy, you might get some pretty good bids right now! Your friend,

The only compelling argument I've heard to have a separate filter for the negative edge is if the pool is large enough (>50K gallons) to require the use of 2 pumps to get adequate turns per day for chlorination and filtration at lower, more energy efficient speeds. Our pool is 35K gallons and only has 1 main filter..no filter for the infinity edge circuit. We have to run the main circulation pump for 20 hours per day in the summer to get adequate chlorination and filtration at low speed on our 2 speed pump. If our pool were larger, we would have likely added another filter and chlorinator and it would have been logical to add it to the infinity edge circuit. Another thing to keep in mind...the addition of another filter and chlorinator doubles the maintenance and replacement expense down the road in addition to initial installation expense. With only one filter, we've had no problems with the infinity edge pit water clarity or cleanliness...it gets turned over 10x per day using another 2 speed pump for the infinity edge which pulls water from the pit and provides water to our waterfalls as well as 4 returns in the main pool. Agree with the other posters....the engineering of the wall and plumbing is highly dependent on the specific design of each pool and how the pool sits on the site. Also, the sizing of the pit is critical along with the adjustment of the autofill level in the pit. Think of the pit as a surge tank with widely varying water levels throughout the day....tile the first 12" or so of the top of the pit rather than just 6" as is normal for the rest of the pool. This will allow the level of the pit to be adjusted lower via the autofill setting so that water loss out the overflow is minimized during surges. When surging is not happening, the extra 6" of tile will ensure the plaster is not exposed for long durations when splash out is not happening and the water level is lower. Surge levels can be minimized by making the pit larger and this is where each PB may differ on how the pits are sized in relation to the main pool area. The larger the main pool area, the larger the pit will have to be sized to accomodate splash out. Think of pit size in terms of inches of water lost from the main pool and resulting volume that ends up in the pit and you'll start to get an idea of how the two are related to each other. Lastly, surge level can be minimized by running the infinity edge pump at higher speeds. This will keep the water moving faster from the pit to the main pool when lots of splashing is occuring. Occasionally, we'll turn our infinity edge pump on high speed during parties when lots of jumping, diving and splashing is occuring. The additional people in the pool also displaces water from the main pool into the pit, so this should also be considered when sizing the pit. Also, remember that filters and chlorinators reduce efficiency of circuits, especially at higher pump speeds. This is another reason not to install a filter or chlorinator on the infinity edge circuit if high speed operation is expected. Some people like the sheeting of negative edges..especially when the water sheet is highly visible (like lakeside lots)...sheeting requires high pump speeds, so desired use of the infinity edge should also be considered in overall design. Our negative edge was primarily for the negative edge reflections and views and not so much the water sheet wow factor...your specific needs may vary. Hope this helps.

Thoroseal http://www.thoroproducts.com/products_waterproofing.htm How long is the outside edge? How many gallons for the basin? It doesn't look that wide except on one side.. I would expect it to be no less than 11" deep, especially with a lot of people in the spa. When heating the spa, does the basin get to go along for the ride too? Does the basin have to spare capacity to capture the spa until they equalize in height, should the check valve on the weir pump's discharge develop a leak or would you lose some spa water to overflow? Scott

With any negative edge, you can expect to need at least a flow of 5 GPM per foot. An edge that has the outside edge higher will want cause the water to want to sheer away from the outer wall. A higher inner edge will want to run along the outer wall. This assumes vertical walls on the outside. that usually means tile, not plaster or high aggregate like Pebble Tec or Wet Edge, etc... This keeps the water coming over the edge close to the wall and minimizes aeration of the water. Aeration will reduce the alkalinity making your pool subject to fairly rapid pH swings, typically a rising pH that can cause calcium scaling, an unsightly whitish and hard to remove deposit. The outside wall and edge surface should be tiled, as should there be waterline tile on the inside, IHMO. You only want one catch basin. The other 3 sides should be narrow channels that lead the water coming over the edge to the basin. This minimizes a trip hazard near the pool. The smaller channels can be covered but will need to drain into the channel easily. Expect water loss. Have an auto filler in the basin since that is where the edge pump system will be getting it's water from. I am not a fan of glass anywhere near a pool, be it a drinking glass or tile. Slivers and chips are often nearly impossible to find until it's too late. Glass tiles have lots of quality issues, even some of the more expensive styles. Regular, ceramic pool tile will provide a much more durable solution and there is an enormous selection available to choose from. Glass tile will have a lot of grout lines because the tiles are normally pretty small, about an inch or so. This will usually mean you will need more water to go over all the edge than the use of larger tiles would to get a true, four sided edge effect. The pool will need at least two pumps and filter combos. One is for filtering the main body and the other for the edge. About 80% of the dirt a pool will accumulate will be removed when the edge is run so the catch basin will get dirty. A 16'x32' pool will have 96' of edge. At 5 GPM per foot, that is a 480 GPM demand. That's going to need a at least a couple large pumps. Even a more precise edge that needs only 2 GPM will need a lot of water and big pipes. Commercial pumps are going to be needed for this. Meet more PBs. Don't just go with a low bidder. Pay for experience. This is not a simple or common design. It also isn't cheap to get done right. If it was easy, Grandma would do it. It is very involved and requires a lot of know how. Not every PB can pull it off. Scott