Question about how much DE to add

dclynds

Well-known member
Apr 29, 2016
84
Houston, TX
Pool Size
17500
Surface
Plaster
Chlorine
Liquid Chlorine
Good day everyone. I cleaned my filter today (Pentair FNS 48 sqft) and recharged my filter with approx 7.5 lbs DE according to the chart on the DE box and not the 4.8 lbs directed by the label on my filter itself. Whoops.

I added 11 scoops of DE using a blue DE scoop. I calibrated it before as 1 uncompacted scoop equals about 0.7 lbs. My filter pressure is 11 psi which is typical for my filter after a cleaning and the return pressure is good. Should I be concerned I overcharged it? Can I simply backwash for a few seconds to remove extra DE if you think I added too much?

Thanks,
Daniel
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
29,863
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
If the filter is not blowing DE into the pool you are probably ok.

Give the filter a really good backwash next time.

If it worries you then do a good backwash now and load in the correct amount of DE.
 

CapeCodPoolman

In The Industry
May 25, 2020
1
Cape Cod, MA
Concerning DE amounts,
I have always been taught,
Blue (shock scoop)= 1lb of DE
Orange DE scoop= 2lbs of DE
&
add 1lb of DE for every 10sqft so a 60sqft filter gets recharged with 6lbs of DE...
Never had any Problems with this method
Good luck
 

TishTash

Bronze Supporter
Aug 8, 2018
155
Merrick, NY
Concerning DE amounts, I have always been taught: Blue (shock scoop)= 1lb of DE, Orange DE scoop= 2lbs of DE, & add 1lb of DE for every 10sqft, so a 60sqft filter gets recharged with 6lbs of DE. Never had any problems with this method.

With all due respect, this isn’t true. As has been posted several times in past threads:

Diatomaceous Earth has a density of 20 lbs/ft3 (unpacked). That translates to 1 lb of DE = 48 oz, which is 3 fluid pints (16oz/pint) or 6 fluid cups (8oz/pint). This is accurate, whether you use “blue” or “orange” scoops. (To be fair, others have cited 13.3 oz coffee containers, which is about as “helpful.”)

One should always follow manufacturer guidelines vs often inaccurate general rules-of-thumb. My Hayward EC65A filter officially specifies 6 lbs of DE for its 27 sq ft of filtration area; this translates to 2 lbs DE per 9 sq ft. Using the often-cited “1 lbs DE every 10 sq ft” formula would result in an erroneous 2.7 lbs, less than half than what’s needed, which would result in suboptimal filtering at best, and permanent grid damage at worst.

(My apologies for the rant, but all the various “tall DE tales” from older posts got me all worked up.)
 
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Remark37

Member
Mar 23, 2017
5
Detroit, MI
With all due respect, this isn’t true. As has been posted several times in past threads:

Diatomaceous Earth has a density of 20 lbs/ft3 (unpacked). That translates to 1 lb of DE = 48 oz, which is 3 fluid pints (16oz/pint) or 6 fluid cups (8oz/pint). This is accurate, whether you use “blue” or “orange” scoops. (To be fair, others have cited 13.3 oz coffee containers, which is about as “helpful.”)

One should always follow manufacturer guidelines vs often inaccurate general rules-of-thumb. My Hayward EC65A filter officially specifies 6 lbs of DE for its 27 sq ft of filtration area; this translates to 2 lbs DE per 9 sq ft. Using the often-cited “1 lbs DE every 10 sq ft” formula would result in an erroneous 2.7 lbs, less than half than what’s needed, which would result in suboptimal filtering at best, and permanent grid damage at worst.

(My apologies for the rant, but all the various “tall DE tales” from older posts got me all worked up.)
This is helpful! I’m wondering how many scoops you do as I have the same filter. I followed mostly but when calculating, not sure about how many scoops. My confusion is the filter states 6 lbs with 26.9 ft2 of filtration area. The scoop says to add one scoop for 7 1/2 ft2 of filtration area. So if I go by the scoop and filtration area, it's about 3.5 scoops. If I go by the weight with a scale, 11.2 oz of de/scoop, it's about 8.5 scoops. So confused!!!

I have the blue scoop in the picture. Thanks sooo much!
 

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