The Thinking Man's Pool

Option #2 - The Cartridge Filter

The second option on the "thinking man's pool" is the cartridge filter.

SECOND OPTION:  CARTRIDGE FILTER

In the 1980's, cartridge filters had a pretty bad name.  After all they were a pain to maintain. 
Some of them had a bunch of little cartridges and they had to be cleaned every two to three weeks.

Cartridge filters had such a bad name that when Sta-Rite Pool Products brought out the first oversized cartridge filter, they did not call it a cartridge filter.  They called it a "Modular Media" filter instead.  Sta-Rite deserves a lot of credit for re-inventing the cartridge filter, and many have followed in its path in the years since.

For the purpose of this discussion, we are talking about cartridge filters that have at least 300 sq. ft. of filter area.

There are several features that make these new large cartridge filters an attractive option:

Feature #1 - Ease of Maintenance

One of the advertising points that Sta-Rite brought out with their Modular Media filter was the fact that it only needed to be cleaned once per year.  They had addressed one of the issues that had made the old cartridge filter so unattractive up to that point.

In reality, we recommend that these filters be cleaned every 3 months or so, because we do not want to oversell them to our customers.  Even if you have to clean this filter every three months, it still makes a pretty good option from a maintenance standpoint.

Feature #2 - Excellent Flow Rate

The flow rate is much better on a cartridge filter for two reasons:

• Absence of a backwash valve

When it comes to hydraulics, backwash valves are a nightmare.  As the water goes through a backwash valve, it takes a bunch of tight turns which slows down the flow of the water.  The cartridge filter uses no backwash valve.  The water goes straight into the filter and straight out. 

In the picture above, the pool has a two speed 1.5 HP pump.  On low speed, it produces 35 gallons per minute and on high speed it produces 80 gallons per minute flow.  If you look at the flow charts for the Duraglas 2 pump, you will find that the system is operating at 50 ft. of Total Dynamic Head (TDH).

If this system had backwash valve, it would reduce the flow by about 10 GPM in high speed and by 6-8 GPM in low speed.   That is a significant reduction in flow.

• Large Filtration Area

The large filter area means that the filter is not going to be easily bogged down with dirt and debris.  The full flow design means that you are going to have minimal resistance to flow.   A DE filter will produce 3-4 additional feet of TDH (as compared with a Modular Media filter in the same tank).  At 80 gallons per minute, this reduces the flow by 3-4 gallons per minute as compared to a similar Cartridge filter.

Feature #3 - Ease of Repairs

The typical DE filter has to be backwashed once per month (or more often) and then recharged with DE powder.  It also has to be taken apart 1-2 times per year and manually cleaned and then reassembled.  Anyone who has tried to reassemble a DE filter knows it can be almost as hard as reassembling a lawnmower. 

A cartridge filter is easy to take apart and easy to clean. Recently, several new cartridge cleaning products have been added to make the process even easier.

Feature #4 - Excellent Water Quality

While it is true that a DE filter does filter more finely than a cartridge filter, the difference is rarely noticeable in most pools.  It is possible to achieve excellent water quality from either filter.

OPTION 3:  SALT WATER CHLORINATION