Backwashing with DE Filter

May 20, 2008
18
0
SE Texas
#1
I've read the sticky on this subject and I am still confused.

We have a 60 sq. ft. Pentair FNS DE Filter. How much DE do I use after backwashing?

As per the sticky I calculated the square footage of my filter and divided it by 8 which is 7.5. On my pool equipment it says one, one pound coffee can equals 7lbs of DE. So I would add just a little more than one coffee can of DE? That didn't sound correct so I called to pool supply store. She said I needed to add 12 coffee cans of DE, that REALLY doesn't sound correct.

When I used to do this myself, prior to gettting rid of the pool service, I thought I put it 4 coffee cans, as per the Pool Builder, but I can't really remember for sure. That has been several years ago.
 

waste

LifeTime Supporter
TFP Expert
Mar 29, 2007
4,160
0
52
Coastalish 'down easter'
#2
Surprisingly, the lady at the pool store was right :shock: A 1 lb coffee can holds ~ 1/2 lb of DE which equals ~ 6 lbs. After backwashing, only ~80% of the initial 7.5 lbs should be added and that comes out to pretty close to 6. I will, however, reiterate that a scoop specifically for measuring DE is the best way to go! (BTW - I'm the dude who wrote the stickie, so this is the same advice :) )
 
May 20, 2008
18
0
SE Texas
#3
Waste - wasn't questioning your method, I new there was something I wasn't doing correctly and of course I was right. I figured out that my "coffee can" is 2 lbs so I only used 7 of my coffee cans.

I looked at two different places locally looking for the "scoop" but neither had it. I plan on ordering it online tonight.

Thanks for your help and the "sticky".