Being in the pool service industry for so many years, I have taken apart and serviced literally hundreds of DE filters
What is a DE Filter?
A diatomaceous earth filter (DE filter) is composed of several grids that hold the diatomaceous earth powder. They are sometimes known in the business as "water polishers" since they are capable of filtering particles as small as three microns (in comparison, a grain of salt is about 90 microns in size). Anything smaller than 35 microns is invisible to the naked eye. This is why I tend to rave so much about DE filters. They are by far the best filtration available for swimming pools.
A DE filter requires back-washing less often than sand or cartridge filters. With a good working DE filter, your pool water will have far fewer problems than other filters. In my article about cleaning a green pool, I could vacuum the pool without by-passing the filter to an external drain source since the DE filter captured every bit. A cartridge or sand filter would have allowed the algae to shoot back to the pool through the returns.
DE Filter Maintenance
Are they easy to maintain? Absolutely.
Here are three DE facts:
- On average, it will only need to be back-washed once a month.
- Grid inspection is recommended after a year. Check for rips or tears on the grid material and rinse thoroughly, as the DE can build up over long periods of time.
- If a grid is torn, it can simply be replaced. It can be recovered, but buying a new one costs about the same and is much easier.
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How to Backwash the DE Filter
This is a pretty simple procedure. After you have done this a few times, you'll get to know what the normal clean filter pressure is for your system. This depends on pump horsepower, returns, etc. They all vary.
In this case, let's say normal clean filter pressure runs around 22 PSI. If the gauge is reading 25 or 26 PSI, that just means the filter is doing its job and starting to get dirty. In this scenario, it would need to be 30 to 32 PSI to indicate that it needs to be backwashed.
Backwash DE Filter Steps
- Before you reposition the "multi-port" valve, be sure the pump is off.
- Select the "backwash" position, then turn the pump on.
- Backwash for three minutes. This will get a lot of the old DE powder out.
- I usually return the valve to the "filter" position, run for another minute, and then backwash again for another minute. This ensures the filter grids are clean.
- With the valve positioned back to the "filter" position and the pump running, you will add around four pounds of DE powder through the skimmer. (Consult your DE filter's owner's manual to discover your filter's square footage and exactly how much powder to add.)
That's it! You're done. Keep an eye on the pressure gauge, and you shouldn't need to back-wash for about a month.
Find Replacement Grids on Amazon
How to Tell If Grids Need Replacing
There is a straightforward way to tell. When you add the DE powder, wait for a minute. If you have torn grids or a broken manifold, the DE powder will come right back into the pool through the returns. Time to take the filter apart!
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.