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Home-pool filters
Cleaning the DE
filter
If the pool has
been inundated with debris due to winds, mudslides, algae and other
conditions, you should backwash your filter in order to flush out
the dirt and debris from the filter. However, the backwashing
process will not get rid of oils from the grids. The oils that
adhere to the grids are a result of body oils, suntan lotions and
even oils found in leaves.
You may start to vacuum your pool and find that the filter will not
hold any more dirt. Since the filter is clogged, there probably is
very little, if any suction on your vacuum. At that point, it is
time to backwash. You may start the backwash procedure, then add
some fresh DE, then get back to your task. Do not vacuum a pool
while backwashing is taking place because the dirt and debris you
vacuum will flow directly inside the grids. You may repeat this
process until you finish vacuuming. When you are done, you may need
to take the filter apart and clean it.
In the process of backwashing, some of the debris will be flushed
from the filter as well and will form clumps at the bottom of the
filter. In fact up to 70 percent of the DE may be removed during
backwashing. You will need to replenish that amount, at least as
close to that amount as possible. If you add too little or too much
DE, clogging of the filter grids may result which will cause the
pressure to build up and it can completely halt the water flow.
Debris in the water from the pool will clog the inside of the grids
when the water is going inside the grid as it flows outward. The
grids will not be useful if this happens. When you have a new pool,
there will be a great deal of plaster dust or gunnite debris in the
water. Do not backwash at this point. However, you may follow a
different procedure so that the dirt will not get into the filter
and pool. If you need to clean the filter, open the strainer pot and
turn on the pump, then use a hose to flood the pot with water; you
may backwash as needed in this manner.
Following is the
procedure of backwashing for a Purex/Hydrotech model of vertical
grid tank DE filter. These types of filters are very common and if
you learn to backwash with this filter, you are able to backwash
with any type.
The first thing you need to do is to turn off the pump and switch of
the circuit breaker. Then open the tank drain so the water may drain
out. Next take off the lid of the filter. You may need to lightly
press on the lid with a screwdriver as you remove the clamp ring.
Sometimes there is a tight seal around the lid with the O-ring, and
when the water is drained, the suction forces the lid on tighter.
The next step is to take off the wing nut on the retainer so that
you can remove the retainer, then remove the grids. It is sometimes
difficult to remove the grids because they are large and curved and
set into the manifold on stumpy nipple type objects. You may put
pressure on the large part of the winged portion of the grid, but be
careful around the nipple object, because a small amount of pressure
could break it off. The best way to remove the grids is to wiggle
them from side to side and pull them straight up, then out. You may
need to hose out the thank while the grids are still in the unit.
But if possible, dig out the dirt and DE before you free the grids.
In order to remove the retaining rod, you need to unscrew it from
the base of the rotary valve. It may be necessary to grip the rod
and unscrew it with pliers if corrosion has set in. Do this gently,
because if it is corroded it could snap off at the bottom if you use
to much force with the pliers in removing it. If it does snap off,
it would leave the threaded end in the rotary valve.
Cont. on cleaning DE article...
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