DE filters are very common in the world of swimming pools. They are used on above-ground and inground pools and are relatively easy for a homeowner to work with.
DE is also an exceptional filtering media, as it can catch fine debris and keep it out of your pool water. Before you go too far down the road of installing one on your pool, let’s understand how they work, compare them to other options, and determine if they are right for you and your swimming pool.
What Are DE Filters, And How Do They Work?
Pool DE filters use a particular substance called Diatomaceous Earth to coat the grids within the tank and filter the water. DE is a natural, fine powder composed of fossilized skeletons of tiny organisms called diatoms. DE particles are very porous because of the hollow nature of those organic structures. They are well-suited for filtering water and can capture extremely fine debris.
Diagram: A) Upper manifold, B) Standpipe, C) Bulkheads, D) Pressure gauge, E) Air relief valve, F) Air relief tube, G) Grids
A DE filter has a set of grids inside the hollow tank, held in place by a top and bottom manifold, pressure plates, and a gasket. The grids have fingers that need to be coated with DE to filter the water properly. Once coated, dirty water is forced through the DE-coated grids, trapping debris. The clean water then exits the filter tank via a valve and heads back to your pool.
The grids can often be agitated with a bump handle or other mechanism that basically shakes the DE around on the fingers and exposes fresh powder to the water, helping it last longer. When the DE accumulates too much fine debris, it’s time to backwash, just like a sand filter.
Unlike a sand filter, you still have some work after backwashing. Before you start filtering the water again, you must add a new dose of DE to the pool filter.
Adding DE is done by pouring some into the skimmer’s mouth; the amount varies by model, but a typical ratio is approximately one pound of DE to every five square feet of filter grids. Doing so is a bit of a messy job, and it is inadvisable to inhale DE.
You may even want to wear gloves, goggles, and a mask to avoid irritating your hands, eyes, and lungs.
Once the DE is mixed with water in the skimmer, it is sucked into the filter tank, where it gets trapped on the fingers of the grids and starts filtering your water.
Pros and Cons of DE Pool Filters
DE filters are pretty common. They are almost ubiquitous on residential above-ground pools, and many inground designs also take advantage of DE’s filtering power. But, there are some pluses and minuses to be aware of if you are considering a new DE filter for your swimming pool.
- Very effective filtering of fine debris
- Relatively inexpensive
- Tried and true filter system
- DE can make a bit of a mess
- DE can be an irritant
- DE needs to be changed frequently, especially when the water is very dirty
Let’s see how those benefits and drawbacks compare to other popular swimming pool filters.
DE Filters vs. Sand Filters
DE and sand filters are similar in that they need to be backwashed periodically. But, sand pool filters can typically run a bit longer before they need a backwash to clean them. They both are equipped with a valve to adjust the water flow and make backwashing possible.
Unlike a DE filter, you do not lose sand from your filter when you backwash. It all remains in the tank. When backwashing a DE filter, you rinse away all of the DE and the dirt caught in it. That means you must add a new DE to a DE filter system each time you backwash.
Since some people are very sensitive to exposure to DE, it can be a bit of a hassle to work with when adding it to the system. It’s also not a good idea to inhale DE if you can avoid doing so, as the dust can’t be healthy for your lungs.
You can always wear a particulate mask to minimize health risks, but that does add another step to the job, and you’ll be working with DE often.
DE also tends to make a bit of a mess. If you add it to the skimmer’s mouth too quickly and overwhelm the suction, some of the DE will float back out of the skimmer and fall to the bottom of your pool, and you’ll need to vacuum it out.
And, even if you are pretty careful, you’ll probably end up spilling some on your deck while adding it and schlepping it back and forth from wherever you store it. It’s easy to clean up with a hose and doesn’t stain. But, it is an eyesore, and if you accidentally rinse it into your pool, you might have to get your vacuum out.
One strategy to minimize spilling is to buy small, single-use bags of DE. Instead of buying a big bag or box of DE intended to last a long time, the smaller bags are usually sized to meet the need for one application of DE after a backwash. But, they are much more expensive.
DE filters also have a grid system, and sand filters do not. So, in addition to the expense of DE itself, you may have to replace the grids periodically if they develop a rip or begin to deteriorate.
DE Filters vs. Cartridge Filters
DE filters and cartridge filters are alike in their design. A system of grids sits inside the tank, and they help to filter the water as it is forced through the tank by the pump. Cartridge filter grids are designed to be replaced and cleaned periodically. Similarly, DE filter grids must be rinsed once or twice per season. If you’re considering a cartridge filter, read my guide on replacing your pool filter cartridge.
So, the tank of a DE filter mirrors that of a cartridge filter tank. A band or clamp typically holds the top and bottom halves of the tank together. Some tanks have trick latching systems or a threaded knob instead of a band or belly clamp.
Whatever holds it together, you open that fastening system, separate the halves of the tank, and remove and rinse the cartridges or grids as needed.
But, DE grids can be rinsed via backwashing between heavy cleanings, while cartridge filters can’t. DE also filters down to a much finer level of debris than either sand or cartridge filters. So, backwashing needs to be done quite regularly.
In comparison, a cartridge filter can keep running effectively for a long time, even when it’s pretty dirty.
A DE filter can’t keep your water clear and clean after it gets clogged with debris, and the tank pressure will build quickly. You should expect that a DE system will require a lot of backwashing when the pool is quite dirty, like when you first open it each season or after a heavy storm.
Sometimes, that will mean multiple backwashes every day until the water clears up. And you will likely have to backwash after each vacuuming.
Lastly, DE filters are typically much more expensive than cartridge filters.
Check out my sand vs. DE vs. cartridge filter guide for a much more in-depth comparison.
Criteria You Should Consider When Looking for DE Filters
DE filters need to be sized appropriately to handle the volume of water in your pool. Look to your filter manufacturer to determine which size is best for your application.
It’s fair to say that DE systems operate in a bit of a sweet spot. If the pool is of moderate size, DE is perfect. If it is very small, a cartridge system will likely be your best bet, as it can handle all the water filtering for long stretches of time without needing to be cleaned.
A very large pool with a tremendous volume of water is probably too much for a DE system to handle, as it will need to be backwashed very often.
DE is a common choice for homeowners taking care of their own pool because it is a very efficient system that is relatively easy to work on when needed. Just make sure that the manufacturer’s specifications are in line with the size of your pool.
Best DE Filter Brands
Brands like Hayward, Pentair, and others are known for making some of the best DE filters on the market, and I tend to agree. For more specifics, check out my guide on the best pool filter.
Tips for Cleaning Your DE Filter
When cleaning your DE filter, you’ll typically only need to backwash it. Shut the pump off and turn the valve to backwash mode. Never adjust the valves while the pump is on, or you can ruin the gasket within it.
Once you’re in backwash mode, turn the pump back on and wait for the water to run clear. If you can’t see it exiting the plumbing because the waste valve is buried, there is usually a sight glass on the valve itself. Once the water is clear, shut the pump off.
Now turn the valve to filter again and run the pump for a few seconds. This will agitate the fingers and shake up the remaining DE. Repeat the process and backwash once or twice more to eliminate as much of the spent DE as possible.
Some valves have a setting to rinse the system. If equipped, run the pump in the rinse setting for about fifteen to thirty seconds. Then set everything back to filter mode.
Periodically, washing the grids of your DE filter may be necessary. It is a good practice to do so once or twice a year, especially at the end of the season. Doing so will keep the DE from growing any algae or mold.
To rinse the grids, open the tank’s clamping system, and set it aside. Remove the top manifold, and open the bottom drain plug on the filter tank. You can rinse the grids in place with a hose. Or, if you want, remove them from the tank and rinse them somewhere else.
You rarely have to disassemble the grids any further than that. But, you can if you want. Though, at that point, you may just want to buy new ones, as it can be a pain in the neck to get everything back together correctly.
How to Add DE Powder to Your DE Filter and How Much to Add
After a thorough backwash, go to your DE stash and bring some to the skimmer. Do not delay adding DE after a backwash, or the grids could become caked with debris and reduce the efficiency of the system.
Open the top lid of the skimmer, and add the manufacturer’s recommended amount of DE. Typically, that will be about one pound of powder for every five square feet of grid surface. A scooper like an old coffee can is very handy. You can read my guide on how much DE to add to your filter for more specific measurements.
Ensure that you add the DE slowly so as not to overwhelm the skimmer. This will help avoid having any DE fall back into the pool itself. When you’re done, put away your DE and rinse any that spilled off the deck, being careful not to get any in the water.
How Long Do DE Filters Last? And When Is It Time to Replace Them?
DE grids can last many years. The fabric of the grids tends to become brittle and deteriorate after ten or so seasons. Though, some users may get more life out of a set while others might not. It’s sort of the luck of the draw and determined by how dirty your pool gets and how well you maintain the balance and chemistry of the water.
You’ll know it’s time to replace the grids if the water seems to remain cloudy even when running the filter for a long time and backwashing routinely. Another sign of needing to replace the DE filter grids is the appearance of DE in the pool.
If there is a bit of DE shooting out of the return jets, it is a pretty good indicator that there is either a rip in the grids themselves or a crack in the manifold.
At that point, it is time to inspect the internals of the filter system and replace anything that is no longer working right. Since DE filters are very common, it is pretty easy to buy a whole new set of grids, and they aren’t too expensive or difficult to change. For more on replacing them, head to my guide on DE filter grids replacement. If you don’t think it’s time to replace them quite yet, you can read my guide on diatomaceous earth pool filter problems to troubleshoot what might be happening.
If you don’t want to open up the tank, it’s probably time to call in a pro.
Alright, that’s about it for DE filters. Have any questions? Drop me a line; always happy to help.
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