Adding DE to sand filter

[The Raddish]

#update-sticky

NOTE: I've moved this thread to this forum so that there is an easy access to adding DE to Sand filters. It's not a PERFECT thread on "how-to" but it will tell you how. I'm add these instructions at the top of the originating post by The Raddish.
CarlD, Moderator.

Here's how I do it:
1) Backwash your filter. Note the pressure it's running with.
2) mix about 1/3 of a cup of DE into a few gallons of pool water.
3) pour the mix slowly into your skimmer while the pump is running. If it's a 2-speed, use low speed.
4) WAIT about 20 minutes and see if the pressure rises. If it does you want it to rise about 1 lb.
5) If the pressure doesn't rise, or rises less than 1 lb, repeat steps 2), 3) and 4).
6) If the pressure has risen 1 lb, you are done. (frankly if it goes up 2 lbs, I'm OK with that. ) A 1 lb rise is your target.
7) If it goes up 5 lbs or more, backwash and start again, but use less DE.

That's it! Everytime you backwash you have to do this again, but once you know how much DE to use, you'll just add that much.

I hope this helps.

Carl


I keep reading about people adding DE to their sand filters to help with the really small particulates that accumulate into the pool. I've already started using a skimmer sock and that has helped tremendously, but I'm thinking maybe a bit of DE would help even more.

How to do you add it? Do I need to remove the multivalve from the filter (something I DON'T want to do), or can I just add some into the skimmer? If I have to remove the multivalve, I guess I'll just pass on the idea, as plumbing hassles will abound.

[CarlD]

Nah, it's a SNAP!

The ONLY thing you have to remove is the skimmer sock!

Start by recording your pump pressure.
Then add 1/3 cup into the skimmer (of course while the pump is on!:p ).
Wait 20 minutes and see if your pressure is up one pound.
If not, repeat: add another 1/3 cup and wait another 20 minutes.
When your pressure has increased one pound you are DONE! Just note how much DE you used (probably a cup or less).

When you backwash, you lose the DE and need to add the amount you figured out above--no need to struggle with checking it again and again.

If you put in too much, your filter will clog, suction will drop, and pressure will rise. Just backwash and you are back to square one!

It's as simple as falling off a log. I bought a 10# box late July early August and haven't even finished the FIRST 5# bag in it! So it's cheap, too!:D

[ScottS]

It's as simple as falling off a log. I bought a 10# box late July early August and haven't even finished the FIRST 5# bag in it! So it's cheap, too!:D
Carl where do you find such small bags of DE? I called most pool stores in my area and they all sell 20-25lb bags.

[CarlD]

Carl where do you find such small bags of DE? I called most pool stores in my area and they all sell 20-25lb bags.

A local pool dealer has them. Runs about $8-$9 a box so it's more expensive per pound than big boxes, but still cheap.

[The Raddish]

Okay, I have now added two cups of DE to my filter with no pressure change, and I'm not inclined to add more. Also, it appears that the DE is floating around in the pool now instead of in the filter, as I can definitely see much more particulate matter by way of the pool light than there has ever been before.

Will this stuff eventually filter out?

I removed my skimmer sock, and added 1/2 cup (couldn't find a 1/3 cup measuring cup) at a time to the skimmer, slowly. I waited about 30 minutes between each add with NO change in pressure.

Did I do something wrong?

[gordyjamz]

hey raddish, I posted a thread about three weeks ago concerning this. I ran into the same problem. I tried the trick and it didn't work. It caused my water to go cloudy. It seems to work for some, and not work for others. I think it depends on the filter. You should backwash immediatly if you feel its not working. It may take a few backwashes to get all the DE out, but once you do, run the filter 24/7 for a few days and it should clear up.

[KurtV]

Raddish, I'd open up the filter and check the condition of the sand. You may well have some chaneling that is allowing the DE through the sand.

Also, what size pump and filter do you have? What is the normal (freshly backwashed) pressure at the filter?

[The Raddish]

The pump is a brand new (less than a week old) Pentair Dynamo 3/4hp two speed pump. I added the DE while the pump was on the high speed setting, and left the pump on high for the 12 hours or so following the introduction of the DE. Even after the pump was set to low, there still remained a lot of particulate matter that could be seen in the pool light.

During the daytime, the pool water does look crystal clear. The only time I can see any particles in the water is when it flows past the light at night.

The filter is a new (installed in early June) Hayward 220T with new filter sand.

I had just backwashed prior to introducing the DE to the filter. The normal pump pressure is 9.5 psi on the high setting.

[CarlD]

Not sure what is going on...unless you don't have sufficient sand in your filter (must have at least 200#). It sounds like you may have a cracked lateral, or the sand isn't distributed correctly.

In any case, I don't think it's a DE problem but the DE blowing out is merely a symptom of a much deeper problem.

[The Raddish]

Okay, I decided not to backwash and let it go a couple of days to see what would happen, and last night I noticed that my water was clearer than it has ever been. There was virtually no particulate matter to be seen in front of the pool light!!

I guess the DE trick does work, and perhaps I just introduced it to the filter too fast or something. At any rate, next time I backwash I'll go a little slower with the DE and see how much I'll need to get the job done. :cool:

[poolmom06]

Does this work with Zeolite sand also?? I have a cloudy pool trying to clear up, my neighbor gave me some DE and I want to try it, but don't know if I should...

[KurtV]

PoolMom,
I've been running with some DE in my zeo-something filled sand filter for the better part of a year now with no ill effects. That's the good news. The bad news is that I see little if any positive effect from adding the DE. My water is very, very clear, but at night I still have visible particles in the light field, with or without DE in the filter.

I will say that I get a faster pressure rise in the filter when I have DE in it. It's obviously catching more stuff, but it doesn't seem to make a bit of difference in the visible water quality.

[Poconos]

Raddish,
Since you have a 2 speed pump, given a choice, I'd try adding the DE while on low speed. You want it to form an even layer on the top part of the sand and it seems to take a while to layer the sand. The 15-20 minutes mentioned. Also, haven't seen it mentioned so far in this thread, but you should pre-mix the DE in a few gallons of water and pour it in the skimmer slowly. I even think they say this on the DE package.
Al

[CarlD]

but you should pre-mix the DE in a few gallons of water and pour it in the skimmer slowly. I even think they say this on the DE package.
Al

oops.:o




Also try skimmer socks in your skimmer. They catch an amazing amount of crud that's very, very fine, like skin oils and pollen and such.

[The Raddish]

Yeah, I've been using skimmer socks for quite a while now, and I am a huge advocate of them. :)

[simsjim]

A neighbor of mine says he uses old pantyhose / stockings in place of the $7.00 skimmer sox. Do you think thats a good idea? (I am curious to ask him what he did with them before they were 'old' pantyhose....:p )

[poolmom06]

oops.:o

Ditto that!!!

[Dr. Spike]

but you should pre-mix the DE in a few gallons of water and pour it in the skimmer slowly. I even think they say this on the DE package.
Al

It does say that, at least on the DE I have. It tells you to mix it with water to make a milk like solution. Or something like that, I am not reading the package, just going from what I remember. :)

[Rangeball]

I add it straight to the skimmer and figure it's nice and it's always nice and milky by the time it hits the filter :)

[Jeffski]

Added DE to my sand filter. Only problem is that it decreases the flow through the filter, so the waterfall from my diving board has less water flowing and sometimes the heater and SWG will shut off due to lack of flow. I am using less DE now than when I first tried it... but even a small cup of DE raises filter pressure by at least 2 psi and I can't imagine that small amount is really doing much inside the filter.

The positive for sure is that if I use some DE before I vacuum then I know it's catching the dirt instead of shooting it back into the pool, which is what sand alone will do. Then I backwash after vacuuming and add less DE for normal pump operation.

[myLABSpool]

Thanks all for the DE tips, I now get DE quality filtering with the ease of sand.

I'm pretty much sold on adding a little DE into my sand filter. After a recent experience with Algae and then cloudy water for the first time (because I let my Chlorine drop too low after a few days of rain and 85 deg water) I had algae growing a fair amount. After brushing and treating the Algae my water got cloudy and did not clear up after a few days. So I added some DE into the skimmer and clarifier (once) to the pool and the water started clearing within hours. I'm not really sure how much the clarifier helped since I've never used it before. I did have to backwash and vac daily for several days, and I kept recharging the DE after each backwash and the water kept getting clearer and clearer.

That was a week ago and my water has never been clearer! It always looked crystal clear before using DE, but at night I'd notice a little fogginess in front of the light. Since using the DE that fogginess is virtually gone and the water is "severe clear."

My only technical input for people, based on my experience, is that I had to add too much DE to get a 1 lb rise ... I had added many, many cups before I saw a pres rise. So I abandoned that and now just add about 2 cups mixed with water slowly into the skimmer. No pressure rise but it really seems to help. With DE added my filter runs around 18 PSI, same as without DE.

Thanks.

18x36 IG vinyl 24k gal
200 lb starite sand 1 hp starite pump

[Poconos]

Glad to hear it's working for you As for the amounts.....whatever works.
Al

[Wayne LaBanca]

So, I tried the DE thing this year. got a 2 pound drop in pressure (this is the first oddity), I find my pressure drops as the system becomes restricted any when from the skimmer to the input side of the sand.

4 hours later, all of the DE was in the skimmer sock which off course blew the prime. :(

So, I'm thinking my pump is pushing too hard for the filter? I run at 18lbs normal. The filter is a Hayward GM140 (takes 50# sand) and the pump I will post when I get home.

Wayne