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Thread: Big spillway

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    Big spillway

    Hi everyone. I think I'm headed for trouble.

    My pool spa design calls for a cascading flagstone spillway that must be about 14 linear feet along the top edge of the spa as it overlooks the pool. It'll cascade down steeply angled ledger flagstone for about 36" to the water level. I've spec'd out an extra 2HP pump and 2.5" pipe for this water feature, but I'm worried that it may still be too much surface area to look nice.

    Is this going to work? I want a big water feature that just trickles. Perhaps I should place breaks along the top edge and have 3 or 4 spillways. Just not sure on this one.

    Oh the problems of being an owner-builder.

    Thanks for the advice!
    Denver, CO

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    Join Date
    May 2007
    South Central NJ

    Re: Big spillway

    A 2 HP pump, will, if all of it's discharge is sent to the spa and it is drawing water from the pool will create a very substantial flow down the ledger wall. If the top layer is reasonably close to level and flat, you would only need 1/2 to 1/3 of the flow. Have a way to direct some return flow to the pool and split the two with a 3 way valve.

    There are many issues to concern yourself with. This is the type of value a PB brings to the table. To those that say "He'll just farm it out to subs" I say,"So what. They do what they are told, they didn't do the design and they are not accountable for the design."

    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

  3. Back To Top    #3
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Big spillway

    Flagstone may not be the best choice. Flagstone is a kind of generic category, so what you get varies. Most kinds of flagstone are relatively soft kinds of rock that split easily into flat pieces. Softer rock that splits easily tends to suffer water damage easily.

    In an application like this, getting the top edge level is very important. That means extra attention to the footers and better than average masonry work. All of that is perfectly possible to get right, but it does require more than the usual amount of attention to detail and offers more ways for things to go wrong.

    You might want to think about getting a variable speed pump for the cascade pump. 2 HP sounds reasonable to me, but you don't know for sure exactly what it will look like until it is up and running. A variable speed will allow you to dial in the flow rate to get the appearance you desire. A variable speed pump does cost more up front, but it will also save electricity, making up for at least some of the extra expense, and depending on your electric rates, possibly saving you quite a bit in the long run.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  4. Back To Top    #4

    Join Date
    Feb 2011
    Sicklerville, NJ

    Re: Big spillway

    I was a little worried about a 2 HP pump handling the 8 deck jets I was installing. I did the calculations and knew it should work fine but still had doubts. When I first turned them on I was shocked to see all 8 shoot over 20' in the air at once when given the full flow of the pump. It moves a surprising amount of water. Like Scott advised, a 3-way valve to adjust flow is a good idea.
    25k gal Lazy-L, vinyl liner, poly walls, swimout spa, diving board, TurboTwister slide.
    Hayward 2HP 2-spd pump, Pentair 2HP spa pump, Hayward 30" 500lb sand filter.
    Goldline Pro Logic PS-8 automation/SWG. 2 LED ColorLogic 4.0. 8 Jandy deck jets. MX-8 cleaner.

  5. Back To Top    #5

    Re: Big spillway

    This great info and thanks all for the advice. On the pool builder thing... this is my second pool and my first pool was done by a pool builder. It wasn't a great experience. He used crappy subs and wouldn't be held accountable for his mistakes. They were not huge errors and not worth the trouble of suing, but very frustrating nonetheless. A couple issues in particular I didn't come to realize until 4 years later... it was the over-sized pump problem and big problem with the pebble finish. Anyhow... new house, new pool build, and quite a bit more knowledge.

    Admittedly, plumbing is harder than I expected, but with the 4 PBs I interviewed first... those guys didn't have much of a clue either. I figured that if there was something I wasn't going to like about the pool it should be my fault and started it on my own. The subs I'm using are all good and the masonry guy is very good. Oh... The flagstone we're using is a type of quartzite. It's very hard.

    I'll post some pics this evening. I'm in the steel and plumbing stages.

    Thanks again!
    Denver, CO

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