Swimming Pool Blog

Top 5 Pool Filter Problems

by John Galcius, March 19, 2009

Last week we covered the Top 5 pool pump problems - well, now it's another week, with another set of problems. Just when you have your pump all straightened out, along come some real nasty pool filter problems. No matter what type of pool filter you have - Sand, Diatomaceous Earth (D.E.) or Cartridge, you will need to do some sort of maintenance or repair to keep your pool filter operating in top condition.

#1 The filter requires too much cleaning or backwashing

The length of time between filter cleanings is called the filter cycle. When the filter is brand new, one might expect the filter to run for 30 days between cleanings. As time goes by, the filter media (DE powder, filter sand, or the filter cartridge) breaks down and or clogs up, and may indicate that it's time to change the filter media. If you find your self having to backwash your filter every week, you probably need to replace the filter media, assuming that your filter is properly sized.

Generally speaking, filter sand will last 5-7 years before the sharp edges become rounded, resulting in less effective filtration. DE filter grids should usually last a little longer, 7-9 years before they begin to clog with minerals or the fabric breaks down and develops holes. A filter cartridge may only last 3-5 years, depending on the work it has been asked to do. Eventually, all filter media will need a replacement, and a good indicator of when to change it is the length of your filter cycle.


#2 Filter media is coming into the pool

Hopefully your filter cartridge is not coming back into your pool - in chunks! DE powder or filter sand, however, is small enough to pass through small enough holes. Filter sand coming back into the pool? Small amounts after backwashing may be nothing much to worry about, but if you have a steady deposit of filter sand laying on the floor beneath the pool return, then you de filter powdermay have a broken filter lateral or standpipe. Cheap parts, but you have a bit of a job removing the valve and the sand to do a complete sand filter inspection.

 DE powder coming into the pool is also common immediately after backwashing. As with sand, however, a continuous stream of the white stuff will indicate a problem internal to the filter. Most common is a tear in the fabric of the de filter grid. It also could be a crack in the manifold which the grids connect into. One of the through-bolts that holds the assembly together may have loosened and this small void may be allowing the DE powder to pass through the tank.


 #3 My filter is not keeping my pool water clean & clear

This is a bit of a trick question, as it may not be the filter that is to blame. Are we running the pump long enough during the day? Is the sanitizer level correct? Are the pump and skimmer baskets clean? Is the water chemically balanced? And the biggest question of all ~ is the filter properly sized? If the answer to all these questions is yes, refer to pool filter problem #1 above. The filter media may need to be changed.

Also make note of any other modifications made to the system recently. Were valves, chlorinators, heaters, or other items added to the filter system? Has a larger (or  smaller) pool pump been installed?

#4 My filter pressure is too high (or too low)pressure gauge for pool filters

The filter pressure guage is an inexact instrument, let's establish that right now. They are known to fail. It should return to zero when the pump shuts off. Sometimes they get stuck on a bent guage face, a flick of the fingernail can help jar a stuck guage.

If your filter pressure is Lower than Normal, this indicates that there is an obstruction or blockage prior to or before the filter. Check for a clogged pump basket or pump impeller. If your filter pressure guage is Higher than Normal, this indicates a blockage at or beyond the pool filter. Check for a clogged filter, partially closed return valve or obstruction inside of a pool heater or a return line.


#5 My filter is leaking

Drip, Drip, Drip! So annoying - probably won't drain the pool! Nonetheless, many pool owners sleep better at night when they know the filter isn't leaking. Usual leaks occur at the belly band on a split tank type of filter. Remove the band, clean the o-ring of any grit and add a small amount of lubricant. Reposition the band, and use a small hammer to tap the band as you tighten. Make sure the band makes full contact with both tank halves.

Drain plugs are common leakers too. When installing, remove old teflon sealant, and reapply. Don't overtighten, as this often cracks the underdrain assembly. If this has happened - a little superglue goes a long way! If there is a hole in the tank, well, start saving for a new filter. I've never had success in patching holes in any type of filter tank. Many filters (OK, most filters) ooze and drip a little. If you can sleep at night, it may be cheaper and certainly easier to live with a little drip.

We hope that these articles are helpful to you! Our pool techs love helping you enjoy your pool!