SAND POOL FILTERS
sand in a pool sand filter (#20 silica sand; 45 - 55 mm) is specially
graded to trap particles in the 20 - 100 micron range. As a sand
filter collects dirt, its efficiency increases, trapping more dirt.
When your pressure gauge shows a reading 8 - 10 lbs. over the clean,
start-up reading, it is time to backwash the captured dirt out of
Sand filters are known to be the lowest maintenance of the three types of pool filters. You may only need to open up the tank every 5 years or so. DE filters require removing the internal grid assembly at least annually to clean them well, and cartridge filters don't backwash, you remove the cartridge and hose clean every so often, depending on the cartridge filter size. Sand filters are the easiest to operate and maintain.
say" that the sand inside a sand filter should be replaced after seven years. Gradual
loss of efficiency may be hard to notice. If your sand filter requires
frequent backwashing, every week or two, the sand bed may be "mudballed",
or it may be "channeled".
It may also "calcify"
with calcium deposits. Other water balance problems
may also contribute to pool filter sand deterioration, but a properly sized sand filter
could go over 10 years between sand changes.
of Biguanide chemicals, i.e., Soft Swim or Baquacil require annual
cleaning of the filter sand to prevent it from "gumming-up". High
amounts of bather oils can gum-up a sand bed. And just the years of
a pump forcing water over the grains wears away the sharp edges of
the sand. Such pool filter sand becomes more circular, and traps dirt less efficiently.
that for sparkling water, we need the trio of sanitation, filtration
and circulation. If one of these areas is lacking, the water won't
look so good. So, if you've kept very good chemical maintenance and
your circulation is good, you may have a filter problem. Is the filter
sized properly? Many filters of the 70's - 80's were grossly undersized,
the trend now in pool filtration is
"Go Big Early." In ground pools should have a 3.1 sq ft sand filter or greater.
a small amount of aluminum
"alum", through the skimmer will form a gelatinous layer on
top of the sand bed, useful in cleaning up an undesirable water condition.
You can also add a small amount of D.E. powder or other
and When do I Backwash my Sand Filter"
the pressure gauge on your sand filter is reading 8 - 10 lbs above the clean, starting
pressure (after backwashing), it is time to backwash your sand filter. This
process involves turning a valve so that the water will flow through
the filter backwards, flushing out the dirt - Hence the name "back-washing." Sand
filters can have either a push-pull valve (also known as a slide valve)
or a multiport valve. The multiport valve has multi-ports on the valve,
usually 6 positions. Always shut off the filter pump before turning the filter valve.
it here all the time, except when backwashing, rinsing
this setting for 15 seconds after backwashing
to rinse the sand filter tank
this if your filter's broken; at least you're
circulating the water
this setting to reverse the flow in the filter
and send water out of the waste line.
Make sure valves are open and your backwash hose is rolled
here to close off flow from the pool, usually
to work on the equipment. Do not operate
pump with valve in the closed position
Another filter bypass setting, but this setting
sends the water out of the waste pipe (hose),
instead of returning it to the pool. This
setting is used to lower pool water level
or to vacuum to waste.
to backwash a sand filter with
a multiport valve;
off the pump motor
down on valve handle, rotate valve from FILTER
to BACKWASH position
out any backwash hose or open any waste line
air bleeder assembly on top of sand filter, and turn
pressure gauge for backpressure and hose
for kinks. Be prepared to shut off pump quickly if the pressure gauge spikes or if the hose kinks up.
- Let the pump run for 2 - 3 minutes
on BACKWASH or until water runs clear
off pump motor and move multiport valve handle
to RINSE position Run on rinse for 15
off pump motor and move multiport valve handle
to FILTER position
pump back on and note lower pressure. Roll
up backwash hose
Backwash a sand filter with
a slide valve (push-pull valve);
off pump motor, roll out backwash hose (if
you have it)
to unlock plunger T-handle, pull / twist
plunger upwards 2 - 3" (PacFab valves are reverse)
air bleeder assembly on filter, and turn
pressure gauge for backpressure (+
30 PSI) and hose
for kinks. Be prepared to shut off pump
hose fills with water, backwash your sand filter for 2
- 3 minutes or until
water runs clear
off pump motor and push T-handle back down
into locked position
pump back on and note lower pressure. Roll
up backwash hose
properly sized sand filter should, in most cases, be able to
operate continuously for a period of 4 weeks between backwashings.
"Filter Run" of less than 4 weeks may indicate sand problems
(or sizing problems). It's a good idea to mark the pressure gauge with "Clean" & "Dirty" marks, or write the numbers on the tank, i.e., 8/16 to serve as a reminder when you need to backwash your sand filter.
in the pool?
news. If it hasn't blown in, or been carried in on the feet of swimmers,
it's likely coming from the filter. A broken lateral or standpipe
may be the cause. You'll need to empty the tank, locate and make the
repair, refill with fresh sand and test. If you have overfilled your sand filter, it is not uncommon to experience a small amount of "blow back" after backwashing. Continued sand leakage during filtration usually indicates a lateral breakage. Don't confuse brown dust as sand particles.
In fact, it's common to experience a small amount of dust blown back into the pool after backwashing a sand filter, even with rinsing first. If you see deposits of a dusty, sand colored material on the pool floor, hit it with you pool brush, if it becomes waterborne as a "poof" of dust, then sand it is not. If you have a problem with fine dust constantly passing through your sand filter, you can vacuum this out to waste after filling the pool first. If this problem continues, you may have sand bed problems, or a sand filter that is too small for the pump.
replace your filter sand, you'll first need to empty out the existing sand in the tank.
One method is to spread a tarp out beneath the filter drain assembly.
Then remove the entire filter drain assembly, turn on the pump, and step back!
The water pumping through the filter will remove most of the sand
out the drain hole. Another method is to remove the drain plug only
and allow the filter to drain for several hours or days. Then, remove
the top dome or multiport valve from the top of the filter.
you have the Triton style dome on the top of the filter, with a side mounted filter valve, you'll need
the octagonal dome wrench to remove the dome. If you don't have a dome wrench, you can use a large strap wrench or in a pinch, a screwdriver and hammer. Once the dome is removed,
gently twist the baffle/pipe out of the way so you can get a scoop
to the sand.
you have a Top Mount Multiport, you may need to cut some pipes
to remove the valve. You can reconnect them later with pvc unions or couplings and some pvc glue.
Once these pipes are cut, the clamp band connecting the valve to the
filter is removed, or in the case of older sand filters, several bolts are removed, and the valve pulls straight up and off. You may need to use a little effort with prying and twisting to release the valve off of the standpipe and flange. Plug or
tape or cover the standpipe so you don't spill sand in it. Then you
can use a shop vacuum to suck out the sand, or you can use a small
cup to scoop out the sand.
very careful as you scoop or suck the sand out, not to knock or break the laterals
at the bottom of the tank. They can be brittle when the get older,
and it may be wise to replace
laterals at the time you replace the filter sand. Once all of the sand is scooped out, use a hose to
wash out the sand beneath the laterals. When the tank is empty of
sand, replace the drain assembly, using silicone
sealant on the threads. Then add enough water to cover the laterals,
so the new sand pouring in won't crack them. Again, if you have the
top mounted multiport, cover the standpipe opening. If you have a
side mounted filter valve, gently push the intake baffle to one side,
or wrap the baffle with a small plastic bag to keep the sand from
entering the pipe as you pour it in.
the new filter sand in! Use only specially graded pool filter sand; #20 silica sand,
45 - 55 mm. On top mounted multiport filters, use care to keep the
lateral/ hub assembly positioned in the center, and on the bottom of the tank.
After each bag of sand is added, make sure it is still centered. It
may be useful to have a helper hold the standpipe in place while the
sand is added.
The best method is to lift the sand bag up onto the tank, and use a razor knife to cut from the bottom-belly of the bag. Keep care not to breathe in the silica dust while pouring, and on older fiberglass sand filter tanks, wear long sleeves to keep from getting "fiber-rash".
the recommended amount of sand only; more is not better! If you don't
know this info, contact your dealer or manufacturer. We have the information on most of the sand filters we sell. Most tanks are
filled only about 2/3 of the way full, to leave enough "freeboard" space
on top. When full, clean and lube o-rings
and reassemble filter top, making sure to use a brush to remove small sand grains. Make sure filter lid is very secure, lids that
blow off can be very dangerous. It's a good idea to replace the o-ring
on the filter domes, if it is distended or dry-rotted.
the filter is started up, start up on "RINSE"
setting first (if you have a multiport valve).
Then backwash and rinse again. If you have a push-pull valve, backwash
first. This final step will prevent putting a lot of "sand dust" into
the pool after a sand change. Note your new pressure, it usually will be less than before the sand change.
filter tanks rarely leak themselves, however leaks often occur in
and around the multiport interface. A common complaint is that water
is leaking out of the backwash port of the multiport (six position)
valve. If your sand filter tank is leaking, or has small cracks in it, replace it immediately. There is no safe, effective means to patch a sand filter tank.
Sand filters can leak from the drain assembly. Try to determine if the leak is from the assembly that is screwed into the body of the tank, or if it is the cap or plug that is leaking. Some sand filter drain plugs have small o-rings or gaskets that need periodic replacement.
may have a push-pull valve, or slide valve as it is sometimes called,
instead of a multiport valve. Leaks can occur through the top
of the index plate, or out of the backwash line. This is a easy
inspection to determine what o-rings need
to be replaced on the plunger.
Leaks can also occur at the bulkhead unions where
the valve attaches to the side of the filter. The bulkhead assembly itself may have loosened. This repair is usually more complicated, as you may need to access the bulkhead from both sides of the filter tank.
Multiport valve repair:
Is water leaking out of the backwash port of the multiport valve? Slight adjustments of the handle may temporarily solve this problem. A more permanent repair may necessitate replacement of the spider gasket inside of the multiport. You may also have leakage up around the middle of the handle on the valve, which external adjustments rarely fix. This usually requires replacement of a Teflon washer and sometimes the spring as well.
they don't last forever. But almost. A new filter may be in order
if your current filter is outdated (20-25 yrs old) and difficult
to use or get parts for. If the filter tank has cracked, usually from
freeze damage or possibly from closing off return valves while the
pump is running, a new
filter is in order. Replacement is usually fairly simple, with
just a few plumbing fittings needed.
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