Have purchased a home with an inground pool equipped with a Triton sand
filter. The filter has functioned well for several years and been
backwashed, as required.
My question is whether the sand in these filters needs occasional
additional quantities due to backwashing losses and/or whether the sand
needs to be changed entirely on some schedule. The user manual for
this equipment seems quite rudimentary and mentions nothing about
maintaining/changing the sand, other than backwashing. Also, I can
find no web site for the manufacturer, just a blizzard of store sites
selling the equipment.
Can anyone out there provide some guidance? and a link to a
manufacturer web site?
Pentair is the manufacturer
Some people say to change sand after 2 or 3 years. I let my go 15 years and
it was still probably OK. Using a wet/dry vac to remove a few hundred
pounds of sand is not that pleasant. I'd avoid this unless you see signs of
The original sand granules have sharp edges which tend to catch debris as it
passes. Over time (think years and gallons), these edges become rounded
off, thus reducing the ability to filter. Most filters have a pressure
gauge that indicates "back pressure" (my term) across the filter. This,
with experience, can help determine when the sand needs replacing.
1) Thoroughly backwash the filter. Then return it to normal service.
2) Note the pressure. If no gauge is present, install one.
3) Over a few weeks, note if the pressure rises and how much. Usually when
it increases 4-5 psi, the filter is getting clogged and it's time to
As the sand loses it's effectiveness, the back pressure will not occur
because the filter is NOT getting clogged. THEN, it's time to change the
sand. My experience in Atlanta, is that I changed the sand after 6 - 7
years of service. It is not difficult. Filter is drained a day before,
then the top is removed and a wet / dry shop vac sucks it all out. Once
empty, inspect the plastic tubes (radials or laterals) inside. If one of
these is damaged it will allow sand to enter the pool, most notable on the
stairs. Replaced as required and pour in fresh sand from pool supply place.
BTW, I looked at the old & new sand under a microscope and could not see
Yes, you certainly can slowly lose sand over time. Backwashing can also
distort the population of sand grain sizes by preferentially flushing
out the smaller grains, which degrades the filtering performance even
though it looks like you have a full sand bed.
Only way to know is to open it up to inspect the level of sand in the
vessel. Typically requires unbolting a bulkhead plate for the valve
assembly on top.
One book I have suggests sand can agglomerate to form "mudballs" from
lime deposits and then you get channels through the sand that negate the
filtering. I have not observed this myself. But if that's so, it is a
reason to change out the sand.
You can put pool acid or lye in there to clean just about anything
deposited on the sand. Inspect a sample to diagose if and what is
deposited, if anything.
Filter sand is quartz sand with sharp edges and screened and graded to
have a certain spectrum of granule sizes. Being quartz it is very hard
and durable. It isn't going to "wear out".
My sand filter is huge, and I used a garden hoe to reach down into it to
scoop out the sand to change it once and inspect the buried plumbing.
Took some time but not that difficult.
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