Operating & Cleaning a DE filter

[packerfan]

The manual for my Hayward EC65A De filter says if the pressure rises more than 10 lbs you should clean the filter.

How do I do this?

[waste]

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Operating & Cleaning a DE filter
(The units I have a lot of experience with are made by Hayward – so most of this applies specifically to them, but the principals apply to all DE filters)
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Basics

A DE filter is one which uses diatomaceous earth (~ skeletons or fossils of prehistoric one celled plants) to remove all but the finest material from the water. The DE is a white powder which is mined in various places around the world which was formed by the evaporation of the water that these critters lived in. The DE is kept in the water flow of the filter because it coats the internal grids or fingers which make up the filters internal ‘nest’ allowing dirt and debris to be captured by the microscopic paths created by the coating. Because of the nature of the ‘paths’ through the DE coating, algae – which is the approximate size of the paths – can easily and quickly congest a DE filter, most DE filter owners find this to be the biggest drawback of owning one. The DE must be added to the filter via the skimmer, with the pump running, the amount to add is dependent upon the size of the filter. When adding DE to a filter, most manufacturers recommend mixing the powder with water before pouring it into the skimmer – I have found that adding the powder directly into the skimmer is equally effective, if you have more than 1 suction source operating at the time of addition. (having a second, or third, suction source allows the DE rich water from the skimmer to properly mix with ‘non- DE water’ from the other source(s) to evenly coat the grids).

However, DE filters, while providing the finest filtration, DO have their downsides! If you do a ‘backwash’ (discussed later) or do a thorough cleaning of the filter, you need to add more DE to it – and, if you add too much or too little, you’ll likely have filter problems! Too much DE will clog the filter and decrease the efficiency of it. Similarly, too little DE will not catch enough ‘dirt, etc” and cause the grids to clog up with the debris, both of which require a manual cleaning of the grids and possibly a chemical cleaning of them. Also, ‘bleeding’ the air out of the unit before adding DE is KEY! – the fresh DE can only coat the parts of the grids that are in water!

Knowing how much DE you are actually adding to the unit is VERY important! The best way is with a premeasured scoop – they are inexpensive and well worth the $ spent, any place that sells DE should have one available. DO NOT USE a 1lb. scoop or canister that is not specifically for DE (ie. A 1 lb. coffee can only holds ~ ½ lb. DE) If you have an accurate scale that will allow you to weigh the container first and then the weight of the DE when it’s full, that’s fine -- just be SURE to know ~ how much DE you add when you are adding it!

Types

There are 2 different types of DE filters:
The first uses ‘fingers’ (fabric wrapped hollow tubes, usually 100/ filter) to collect a layer of the DE on. This style is also known as a ‘bump’ filter because the DE can be ‘recharged’ via the use of a handle which moves the whole assembly up and down to expose new pathways in the DE coating without having to replace any DE (I’ll talk about ‘bumping” a filter in a minute.) (There are some ‘grid’ filters which have a handle on the top connected to a plastic plate which operate the same way)

The newer models have a series of grids to collect the DE and either have a multiport valve or a ‘push/ pull’ valve (of which I will speak very little). These units allow you to ‘backwash’ most of the DE out when the filter needs to be cleaned. (* some localities do not allow wasted DE to be flushed into sewers or even onto your own property – in that case a ‘separator’ would need to be installed on the backwash line).

Start - Up

The fabric which holds the DE does very little to filter the water! As such, a DE filter needs to have a coating of DE on the grids/ fingers as soon as the pool is started up. Your installer or pool tech should do this for you the first time and give you a complete lesson on operating your pool (called ‘pool school’- it’s a lot of info all at once and it is very understandable that some of the info is forgotten by a pool owner). The amount of DE required by each filter is determined by the size of the filter – there should be a label on the filter identifying the size of the unit and how much DE it requires when completely clean. As said, KNOWING how much DE you are adding is key! Make sure to note what the pressure gauge reads when the unit is clean and freshly coated with the DE!!

Maintenance

Your filter should run anywhere from 8 psi to 20 psi with fresh DE put in it, depending on your pool and filter system. When the psi rises 8, it’s time to clean the used DE out of it. (when doing any filter work, turn off the pump!)

Bump filters:
1) open the air valve on the top of the unit for ~ 5 sec. and close (bumping with the unit full of water will harm the unit!)
2) Slowly push the handle down and quickly raise it up 4 – 6 times.
3) Now turn the pump back on and see if the psi went down, if it didn’t drop more than 2 psi, you need to dump the used DE.
4) (if you need to dump the DE) – Open the drain outlet on the filter after doing steps 1 and 2 and run the pump for 20 seconds. Close the outlet and run the pump for a minute (don’t do this if you have an algae problem! The uncoated parts of the fingers will collect algae too quickly and clog), then repeat the procedure (make sure you open the air relief while the pump is running until water comes out of it)
5) At this point, you have removed ~ 80% of the old/ used DE so only add 80% of the DE you would use in a new or fully clean filter!!

Grid filters:
1) Pretty much the same as bump, except you have a multiport which allows you to backwash the filter when the pressure rises 8 psi.
2) (always!! Turn off the pump when changing multiport positions!!) Turn the multiport to ‘backwash’ and restart the pump, watch the view-glass or the end of the discharge hose to see when the backwashed water becomes ~ clear. When it is fairly clear, turn the multi to ‘rinse’ for 15 – 20 seconds and then back to ‘backwash’ until the water runs ~ clear again. Repeat the ‘rinse/ backwash’ until the water comes out clear when backwashing, add a short ‘rinse’ and the filter is about as clean as you’ll get it using the ‘backwash’ function.
3) If the water in the pool is fairly clear, I’ll throw in a 1 min filter cycle and do the ‘backwash/ rinse’ cycle(s) again.
4) At this point, you have removed ~ 80% of the old/ used DE so only add 80% of the DE you would use in a new or fully clean filter!!

When bumping/ backwashing doesn’t work:

Sometimes just ‘dumping’ the old De isn’t enough to get you back to proper filter performance – this can be caused by algae (or some other fine debris clogging the DE), or neglect (you didn’t clean the filter soon enough), or the grids/ fingers getting clogged up.

At this point, you need to take the filter apart and manually hose them off (it’s a wet process – so be prepared to get ~ soaked). I recommend the manual hosing every year (I like doing it in the fall when the pool is being closed because, then you know the filter is ready for another season)

If , when manually rinsing the grids, you notice that water is staying in the membrane for more than ~30 seconds, it’s time for a chemical cleaning!

To chemically clean the grids/ nest:

1) Have a bucket/ container large enough to hold the entire assembly
2) #1 Add some TSP (tri-sodium-phosphate) to the water or some electric dishwasher detergent to the water and soak the grids for 3 hours – this will ‘de-grease’ the membranes and is the first step in cleaning them, rinse with hose and get ready for step 3.
3) Dump the container, refill with water and add muriatic acid* to the water so that you have a 10:1 water: acid mixture and soak the grids for another 3 hours, this will clean any calcium off of the grids. Rinse grids again and reinstall them in the filter.
4) Now, run pump and bleed off the air from the filter and add 100% of the DE the filter calls for.

If anything is unclear, we'll be here to help:cool:

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POOLDOC NOTE: All though I can't confirm this, I have seen many manufacturer cautions to the effect that you shoujld ALWAYS remove grease with a detergent BEFORE using acid. The claim is that reversing the order can chemically 'fix' the grease so that it can't be removed. In other words, be SURE to follow the order Waste has given!

[StevenHB]

This is a great write-up. Thanks for taking the time to write it.

One question: How much TSP / dishwasher detergent should be used?

[waste]

It's ~ 1 cup to every 5 gallons of water :cool:

Happy pooling to all!:)

[Hillboy51]

You are the MASTER! I have been battling a cloudy pool for over 3 weeks now. My filter is a Nautilus NS-48 DE. I replaced just about everything you can name: backwash valve, o-rings, filter cells. I have taken apart the filter and cleaned it 4 times in the past month. No matter what I tried, I could not get the pool to clear. Equally puzzling was the fact that the pressure was way too high - 20 to 25 when it should have been around 10 to 15. I was on eBay looking to purchase an entire new set of filter cells (as a last resort) last night when I read your post. It rang a bell because I remembered that water did not drain from the filter cells when I removed them from the case. So very early this morning, I cleaned my filter using your instructions. My pool is now back in operation, the pressure is back to normal and clean, clear water is being pumped into the pool. And all it cost me was $3.00 for the dishwasher detergent! I am writing this in a state of grateful shock. I was at my wits' end and now it looks like we will be able to use the pool this weekend after all. I don't know what to say expect THANK YOU!!!

[waste]

Hey, that's why I come here:D

I get so much help that I use in my day to day work from this site that I figure the least I can do is share some of my experience :cool:


Hillboy51, welcome to the forum! (if you went to prep school in Pottstown - I'd be Hillboy85 ;) )

Thank you so much for the warm words! :o

[packerfan]

hello i just opened my pool for the year and the water was really nasty green and smelled. i precoated my hayward wc65 DE filter and the pressure was at around 14lbs. after running it most of the day i've watched the pressure and everytime it went up 10 lbs i would bump it and then start over again. now toward the end of the day,my starting pressure right now is around 28lbs. is this normal and should i clean this filter pretty soon and replace the DE? one other thing i notice is after bumping the filter and then turning the pump back on, i get some dark looking substance that comes out the return lines and then blends in with the water,this only happens for a short time. i'm still learning this DE thing. thanks Randy

[waste]

At this point, you're probably better off breaking the unit apart and manually cleaning it - then, just add the full 6 lbs and not worry much about it for the rest of the season:)

[packerfan]

thanks for the reply, i believe thats what i need to do also. i'm learning about these de filters and that some people say in the startup season they sometimes pull their filters apart a couple of times and clean them before their good for the rest of the season. the advantages over a sand filter is what again?

[Watermom]

Advantages of a sand filter --- only having to backwash once or twice a month at most which involves turning the handle on the top of the filter into a couple of different positions and then back to filter. Takes about a total of 2 minutes. So, maybe 4 minutes per month. Nothing special to do at spring start up either. Hook up the pump and turn it on. Good to go. Just my personal opinion, but I would never have anything but a sand filter. Of course, a lot of people say the same thing about DE. Personal preference.

[packerfan]

i agree with you for the most part and after reading it i say to myself why did i switch to DE. After having several sand filters over the course of 16 yrs, i couldn't stop sand from appearing in my pool, no matter what i did. new filters,different sand,etc. so i got frustrated and changed. i didn't know this DE would require so much work when opening my pool though. oh well got it now so will use it.

[kingbud]

"A 1 lb. coffee can only holds ~ ½ lb. DE"

Hi- what about the modern plastic coffee cans that hold 33.9 oz. of coffee? I'm thinking they measure about .102 cu. ft. but am having trouble getting an answer on the actual wt/cu ft of the DE filter media. Does 14 lb/cu ft sound right? that would make the plastic jugs hold 1.43 lb. of DE.

By the way the hill beside my pool did not slide and collapse my pool wall, even with the wettest winter an spring in a long long time.:rolleyes:

...(your treatise on DE filters is terrif.)

[kingbud]

OK, figured it out, if a 1 lb coffee can 4" dia x 5.5" long holds 1/2 lb, how much does the bigger 33 oz plastic jug hold? the math was simple, works out to 1.1 lb or something. Silly me, never mind. Thanks all.

By the way, our first pool had a DE filter and it worked great except for once when a cracked manifold was letting DE into the pool, so DE is all I have ever known. I bought a new Hayward 48 sf Progrid last year and love it. Backwashing is much simplified

[kingbud]

ah, yes, a little scientific weigh-in using the ultra precise UPS package scale endorses my hazy calculations, figure 1.06 - 1.1 pounds DE to fill the large, modern, plastic coffee container.

[stlbill]

It's ~ 1 cup to every 5 gallons of water :cool:

Happy pooling to all!:)

I've been using TSP substitute liquid from Wal-Mart with success, but now see real TSP in powder form at Lowes Home Improvement stores. The above ratio sounds like a liquid measurement. If using TSP powder what is the ratio? Thank in advance!

[FRANCIS]

My Hayward EC-65 Perflex manual recommends soaking the nest in 20% strength muriatic acid blended with water 1:1. So why does Waste mention 10:1?

[PoolDoc]

Dunno.

Either will work. BUT, most DE filters do NOT need acid. Acid removes calcium scale, which is somewhat rare. TSP removes body oils, etc, which is universal

ALWAYS, do TSP first. Acid reportedly 'sets' grease, creating irremovable goo.