A close look at waterlines
I am getting ready to build a pool with equipment approximately 15 feet below water level. I have not done this before. Are there any special considerations I should be aware of?
Many builders do not like to put equipment below water level. They have a litany of reasons, but most of them are not based on fact.
Hydraulically, the pump operates exactly as if it were at water level. If the pipe runs are the same, there is no increased head pressure for this situation because the vertical discharge pressure increase is balanced by the positive pressure on the suction side of the system.
There are, however, a few special accommodations that should be made when placing the pump below water level.
All in all, I like to have the equipment below the pool. I believe there are more pros than cons in this application.
All suction lines should be valved independently. Discharge lines should also have isolation valves. Cleaning the pump strainer or doing other routine equipment maintenance is almost impossible whitout isolating the equipment first. Do not depend on a check valve on the discharge side to do this job. If there is debris in the valve, there will be a deluge at the equipment pad when you remove the pump lid.
If you are in a area that ever freezes, be sure to include a freeze-protection system. Broken plumbing at the equipment pad with result in draining the pool - not a very comforting thought.
If you use air blowers on your spas, be certain that is a loop in the supply line above the spa level. The blower does not have the capability to blow water out of lines that are more than 4 feet below the spa water depth. If you bring air into the floor of the spa, you should always loop this line. The blower discharge into the jets will be assisted by the venturi action of the jet itself.
All in all, I like to have the equipment below the pool. I believe that there are more pros than cons in this application. For example, there is never a problem with pump priming.
I am interested in placing some rock
below the waterline on a pool I am building.
Can yo let me know how to do that?
A rock waterline starts long before the mason gets to the job. Indeed, the placement of the rock on the ledge is only the last step in the process.
Before the rock is placed, you must waterproof the entire ledge.
First, a small ledge must be created in the gunite structure for the rock to sit on. Normally, this ledge is 6 to 7 inches below bond beam height. The depth of the ledge can vary from 2 to 5 inches, depending on the thickness of the rock you are going to use; just be sure to allow enough of a ledge to give the rock a solid place to rest.
The pool structure needs to be engineered for this detail. The steel, for example, is normally held back so that it is not exposed when the ledge is cut in the gunite. Also, the pool wall is usually a little thicker than normal to facilitate a regular bond beam behind the ledge.
Before the rock is placed, you must remember to waterproof the entire ledge. I suggest that the waterproofing start a the top of the bond beam and then continue across the bottom of the ledge and slightly down the face of the pool wall. The reason to continue down the pool wall is to ensure a good water seal. It seal around all the irregular edges of the waterline stone.
Finally, rake all the joints to minimize any visible grout. A rock waterline always looks best when the rock is carefully selected, arranged and grouted so that he joints are as small as possible.
If you do all this, rock waterlines can be a great way to add a custom look to your pools. The cost is minimal, and the visual impact is outstanding.