Filter
Comparison Chart
The best type of filter
depends on the usage of the pool as well as the preferences of the
pool owner/operator and the local city codes. The chart below will
help you to determine the best filter for your situation.
| Filter
Type |
Sand |
DE |
Cartridge |
|
Filter
Media |
Sand |
Diatomaceous
Earth |
Paper
Filters |
|
Filtration
Efficiency |
Good
40
microns |
Best
5
microns |
Good
10
microns |
|
Cleaning
Method |
Internal
Backwash |
Internal
Backwash |
Disassemble
and Clean with Hose |
|
Backwash
Line
Required |
Yes |
Yes |
No |
|
Frequency
Of
Cleaning |
Every
Week |
Every
4-8 Weeks |
Varies
Widely, depending on unit |
| Recommended
Application |
Home
Pools
Apartment
Pools |
Home
Pools
NOT
for Apt. Pools |
Home
Pools
NOT
for Apt. Pools |
|
Water
Clarifier
Needed? |
Sometimes |
Never |
Sometimes |
| How
Often Media Replaced? |
6
years (home use)
3
years (apt. use) |
Each
Backwash |
2-4
years |
| Cost
to Replace Filter Media |
$50
- $100 for sand
(excludes
labor) |
$2.00
- $4.00 for DE
$200
- $300 for a new set of grids
(excludes
labor)
|
Varies,
but can be VERY expensive |
| Annual
Maintenance |
None
Required |
DE
Filter Clean
$75.00 |
Cartridge
Cleaning periodically. |
| Positive
Points |
Easy
to backwash
Filter
Media cheap
Infrequent
Repairs |
Best
filtration |
Simple
to maintain
Easy
to repair |
| Negatives |
Poorest
Filtration
"Wastes"
water in weekly backwash |
Backwash
a bit complicated
Repairs
not cheap
Not
allowed in every municipality. |
Cartridges
can be a bit costly, check cost before buying filter.
Filter
cleaning not as easy as others |
The choice of filter
for a home pool is largely up to the consumer. Any type of filter
will work, but sand filters will not filter as finely and this can
create water clarity problems from time to time. DE
and Cartridge filters should NOT be used on semi-public pools
(apartments, condos, hotels, etc). The manufacturers may try
to sell them for this application, but they are not the best choice. The
problem is that with their finer rate of filtration, they fill up with
dirt very quickly and become clogged and ineffective. I have seen
a lot of DE and Cartridge filters that have been pulled off of
semi-public pools after only a few months or years.. In these
cases, the owner had to foot the bill to have a new sand filter
installed. In some cases, where it is not possible to install a
backwash line for the pool, a Cartridge filter may need to be installed,
but it should be done with the expectation of higher maintenance labor
and parts costs. Filter
Sizing Once
you have chosen the right type of filter for your pool, it is important
to get it sized properly. It must be sized to match the pump which
in turn must match the circulation needs of the pool. If the
filter is undersized, it will fill up quickly and also can be damaged by
the force of the pump. If the filter is undersized, it may not
backwash well.
| Recommended
flow rates for different sizes of SAND FILTERS |
| Tank
Diameter |
19" |
21" |
24" |
30" |
36" |
| Surface
Area |
1.8
sq. ft. |
2.3
sq. ft. |
3.1
sq. ft. |
4.9
sq. ft. |
6.9
sq. ft. |
| Max
Flow Rate |
40
GPM |
50
GPM |
60
GPM |
100
GPM |
140
GPM |
| Recommended
flow rates for different sizes of D.E. FILTERS |
| Surface
Area |
24
sq. ft. |
36
sq. ft. |
48
sq. ft. |
60
sq. ft. |
72
sq. ft. |
| Max
Flow Rate |
48
GPM |
72
GPM |
96
GPM |
120
GPM |
144
GPM |
| Best
Flow Rate |
36
GPM |
54
GPM |
72
GPM |
90
GPM |
108
GPM |
| While
the manufacturers will specify the Max flow rate, we
strongly recommend staying with the Best flow rate to
avoid crushing grids due to high pressure. |
| Recommended
flow rates for different sizes of CARTRIDGE FILTERS |
| Surface
Area |
100
sq. ft. |
200
sq. ft. |
300
sq. ft. |
400
sq. ft. |
500
sq. ft. |
| Max
Flow Rate |
38
GPM |
75
GPM |
112
GPM |
150
GPM |
150
GPM |
| Best
Flow Rate |
30
GPM |
50
GPM |
75
GPM |
100
GPM |
125
GPM |
| While
the manufacturers will specify the Max flow rate, we
recommend choosing one within the Best flow rate for
best filtration and better dirt loading capacity. |
Note that these
recommendations are only approximations based on typical
conditions.
On-site
analysis must be done to insure that the filter matches up properly with
the pump and the pool. For instance, if the plumbing runs on the
equipment are particularly long, then the resistance to flow in the
piping will be greater and intake lines may need to be larger than
specified in this chart. Note
also that this may differ from the recommendations listed by the
manufacturer . The
literature may indicate that it is OK to match up a 2.5 or 3.0 hp pump
to a 60 square foot DE filter, but we never recommend it because we have
seen plenty of DE filter grids blown out by these larger sized
pumps. It is always better to oversize the filter. With an
oversized filter, the water flows through the filter media at a slower
velocity and that results in finer filtration and longer filter cycles. Some
builders will install a 3.0 hp filter pump on a pool/spa combination in
order to give maximum water flow through the spa jets. This
is nice except for the fact that the pump is so powerful that it has the
potential to damage the grids in the filter. The better way is to
install a smaller filtration pump for the pool and then run a separate
booster pump. This keeps you from having to run a large 3.0 hp
pump every day on the normal filter cycles.
|
