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De Filter Precoating After Backwashing


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#1 dogfriend

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Posted 20 May 2010 - 05:13 AM

I have a Hayward DE-2400 model filter and my question is:
How much diatomaceous earth (DE) should I precoat the filter with after performing a 2-3 minute backwash?

One suggestion that I've received is 1 pound of DE per 10 square feet of filter area. Well, I can't say that I, as the end user, have a very good estimate of how many square feet of filter area the filter grids make up...

Anyone have any ideas for how much DE I should use to precoat after backwashing?

Incidentally, on start-up (totally clean filter, not backwashed), Hayward specifies 3 pounds of DE.

I would sure appreciate any help on this one. Thanks.

#2 PaulR

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Posted 20 May 2010 - 06:32 AM

Typically you'd figure that a backwash doesn't completely flush out the old DE. How much stays behind, though, is something of a guess. I've been told to recharge with 2/3, or 3/4, or 80%, or even 100% of the full amount. This is one reason to periodically open it up and clean it all off, so you know where you're starting from. (One time somebody said they never backwash, they always open up the filter and hose it off every time.)
--paulr

#3 Pool Clown

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Posted 20 May 2010 - 09:14 AM

You said that you backwash for 3 min. Is that how long you are running the pump? You should run the pump till the water out the backwash is clear, turn the pump off, wait about 5 sec. then turn it back on and repeat till you're not getting any grey water when you turn the pump on.

Factory Warranty/Service for:
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and Paramount pool cleaning systems.


#4 wsommariva

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Posted 20 May 2010 - 09:33 AM

Check the manual or call the manufacturer. I was told to use 60% of the start up amount after backwash. Also, was told to not backwash until needed again per manual. In my case, when the psi goes up 10 points. Also the filter should have the sq ft on it somewhere.

#5 dogfriend

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Posted 20 May 2010 - 09:34 AM

You said that you backwash for 3 min. Is that how long you are running the pump? You should run the pump till the water out the backwash is clear, turn the pump off, wait about 5 sec. then turn it back on and repeat till you're not getting any grey water when you turn the pump on.


Ok...
Normally, I never backwash. I just clean the filter every couple of months when the pressure is high enough. I can explain why I do this if you want.
I'm backwashing lately because I'm in the process of lowering the way-high phosphates in the water. I've been told to backwash for 3 mins. or so during the course of this chemical treatment that I'm doing vis-a-vis the phosphates.

Just wondering how much DE to put in after the 3 mins. of backwashing for this get-rid-of-the-phosphates (mostly at least) work. Thanks-

#6 dogfriend

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Posted 20 May 2010 - 09:41 AM

Check the manual or call the manufacturer. I was told to use 60% of the start up amount after backwash. Also, was told to not backwash until needed again per manual. In my case, when the psi goes up 10 points.


I have the manual and nope, it doesn't list the amount to precoat after backwashing. What was Hayward thinking?!
I've communicated with Hayward over the 'net and, well, for such a simple question, they got their head in a pile of DE so far as I can tell. Must be drinkin' out of the New Jersey chemical Superfund sites. They're like, "Duh, here's a link to how to do a backwash." - no DE amounts listed to precoat after a backwash of a DE-2400. They didn't answer my simple question: How much DE for a Hayward DE-2400 after backwashing? Fools. As bad as Pentair and their awful underwater lights that they (at least for tech. support) seem to know precious little about. Some of these companies really reach the bottom for tech. support in my experience.

Thanks for the 60% number. That is better than the ignorant response from Hayward.

#7 Pool Clown

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Posted 20 May 2010 - 04:21 PM

It's because they are assuming that you are backwashing properly, and are able to remove most of the de. Why don't you back wash as i have outlined, then open your filter tank and see how much de is or is not there, then go from there.

Factory Warranty/Service for:
Jandy, Pentair, Sta-Rite, Raypak, Polaris,
and Paramount pool cleaning systems.


#8 dogfriend

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Posted 21 May 2010 - 10:32 AM

Thanks for all the replies.

#9 BoatingDave

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Posted 26 May 2010 - 07:30 AM

It's because they are assuming that you are backwashing properly, and are able to remove most of the de. Why don't you back wash as i have outlined, then open your filter tank and see how much de is or is not there, then go from there.

but if most of the DE is removed, wouldn't he want to recharge with 100%? (or close to it?)

#10 Pool Clown

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Posted 27 May 2010 - 05:03 AM

Absolutely. I don't agree with the 60% after backwash.

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Jandy, Pentair, Sta-Rite, Raypak, Polaris,
and Paramount pool cleaning systems.





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