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Thread: Pond parts, including pipe, valves and similar plumbing....

  1. #11
    Sansai Arthur's Avatar
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    Dec 2003
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    Beware of PVC Fittings

    I rarely disagree with MCA but this time I felt compelled to post.

    Not all PVC fittings are created equal, despite the standards! The most consideration we should give them is in their flow resistance (as the standards take care of their pressure resistance).

    The easiest way for you to take my meaning is to compare a 90 Elbow from Colonial or Spears to one from Charlotte (in the US). The Colonial and Spears fittings have a smooth round INSIDE shape while the Charlotte inside shape is almost square. The latter will create more back/head pressure and be much more susceptible to water hammer (which happen with high water velocity in systems all too often built with pipes that are way to small for the flow). Head pressure will significantly reduce the water flow (in complex system this is NOT negligeable), high flow velocities that cause hammer, may (and will over time) cause pipe ruptures at the glue point.

    Some PVC manufacturers are more agressive than others at upgrading their molds for PVC fittings. Even the best have flaws in certain size fittings. One should always evaluate a fitting for flow individually and make a purchase decision based on what they see.

    Basic rules of thumb:

    1) always evaluate the flow capacity of all fittings you purchase;
    2) match the fitting grade to the application:
    a) DWV (Drain, Waste and Vent) fittings are OK for gravity feed
    (unless there is a Flex pipe joint, in which case, the joint glue
    length is too short, switch to Schedule 40);
    b) always use Schedule 40 PVC at a minimum on the pressure side
    of the system (I have seen systems built with Schedule 20);
    c) consider Schedule 80 is locations of stress, such as from the
    pump output port before it is expanded to the proper pipe size
    for the flow (when in doubt, use a Schedule 80 fitting).
    3) when using flex, always (when possible) use "long" fittings, and
    fast welding glue, and HOLD the fittings together for at least 10sec,
    when glueing, or they will slip apart to an unknown degree that may
    compromise the integrity of the system in the future.

    I hope this helps.


  2. #12
    Join Date
    Dec 2003
    Cayman Islands
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    Help? Yes, indeed -your reply was most valued.

    It is through advice like that given above we are provided information not otherwise available from any other resource.

    For example, until MCA's wonderful wife, Toni...sat me down and explained the difference in bottom drains that I had my first lesson on the value of bottom drains.

    Now, above I learned that there is a difference in pvc pipe and that flex pipe is now available in 3'.

    Thus, to each of us who have ponds (and, who reading this thread doesn't?) - for certain everyone's contribution to this thread will bring quality, required and vital information important to the keeping of our valued Koi.

    In the final analysis every contribution has value and is vitally important to someone - and, is as important as which 'new' filter has come to the marketplace, which breeder is offering the next GC, or whether natural additives are in fact, natural.

    I eagerly hope that those more experienced 'koi' pond 'builders' will jump onto this thread and add their valued experience to our common knowledge.

    I am convinced that each who are following this thread have some thing of vital importance to share-if only, they will...

    And, let's hope that they will-

    Therefore, regardless of how mundane "you" may feel your input may be, it is welcomed information to someone reading it...and, learning from your good advice and experience...

    Again, all the best

    Grand Cayman

  3. #13
    Honmei MCA's Avatar
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    Dec 2003
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    I was not specific enough

    Lee and all,

    Sorry I did not specify that I am ALWAYS purchasing white schedule 40 pressure PVC pipe. I never use the low pressure drain/waste/vent stuff for the pond. In fact, I don't think I have ever used it for anything.

    In Lowes those 2 types of pipes and fittings are usually near each other in the plumbing section but not mixed up. The diameters of those two different types of pipes and fittings do not match up with each other. So you have to go out of your way to mixed them.

    When glueing up the pipe and fittings, I always use purple primer and heavy duty PVC glue. You can also use the blue PVC glue. Between purple primer and blue glue, you should be able to visually check if a joint has been glued. Finding an unglued joint after the pond is up and running is no fun!

    Again, even for my 4" lines from the Spindrifters, I always use PVC schedule 40 pressure pipe. Typically that pipe is bold white while the low pressure pipes are green, black, or off-white.

    Also consider oversizing your pipe. For example, even if your pump has 1.5" ports, use a 1,5"- 2" adapter and then 2" pipe everywhere. The cost difference is minimal and the backpressure reduction can be significant. Going from 1/5" to 2" usually is not too much of a problem. Going from2" to 3" can be a pain.

    Lee, Toni said "Hi". She is a good teacher indeed. And she has the patience to put up with me!!! :lol:


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