While sand systems are very popular because of their simple operation, they have one considerable drawback as compared to diatomaceous earth filters (besides their high installation cost) and that is the large water volume that is discharged during backwash. Multi-cell filters, however, can backwash in stages and thus produce less volume of sewer loading at one time.
Another common design is for the filter tank to be part of the concrete surge tank with the pumps and face piping in the below grade level of the natatorium. Such systems usually feature a two level filter room with open space over both levels.
If a project is in the Sunbelt states and budget is severely under pressure, an exterior filter location can be justified. With regard to the long-term experience of the equipment versus that of equipment indoors, it can vary. They will likely age quicker than those that were shielded from the UV light of the sun as well as rain and subsequent freezing of the rain during ice storms.
Fiberglass tanks will likely be affected by the sunlight much more if outdoors and eventually can begin to break down resulting in the failure of the tank. The prevention of this type of solar impact is to coat the fiberglass filters or any fiberglass material, i.e., hair and lint strainers with one or two coats of epoxy paint. This creates an opaque covering over the fiberglass that will be effective for several years before it is required again.
Nemato filters are manufactured in Canada and were sold through US Filter prior to them dissolving. Since, Nemato has been approved in CH specs. CH was allowing the US Filter 100 PSI tank on all projects and the National filter 50 PSI tank on most seasonal projects. The National filter was not included in the standard CH specs.
Neptune-Benson manufacturers all of their filter tanks in lengths of 10 ft. For filters longer than 72” in length, the extra material is discarded. For example, if you specify a 48” x 96” vessel, the owner is essentially paying for a 48” x 120” filter since the remaining 2 ft that are trimmed off are not reusable. For 48” x 72” vessels, the remaining 48” x 48” is reused for a future filter (48” x 60” and 48” x 48” filters are handled similarly). Therefore, 48” x 72” is the most economical filter.
In Nebraska, two visually separated pools are not allowed to be on the same mechanical A variance was initially granted for the Kroc Center providing minimum turnovers were maintained; however, this design was not pursued by the owner.
CH Standard: A sand high rate pressure filter system with a semi-automatic backwash system is recommended.
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