I was concerned that my numbers didn't match, because Tapla and others have reported up to 60% waste (fines) when sifting Turface and my numbers were not even close to that. I later found out why: I was sifting with Fiberglass insect screen, not aluminum. Fiberglass has rectangular mesh, 1/16 x 1/32 vs aluminum being 1/16 square. I was fortunate because I live in a hot arid climate and definitely need the slightly smaller particles. There is still no PWT in my containers even using the fiberglass and I use a smaller #10 grit size.

========================= Original Post ===================================
Here is some data I gathered last year when I did my initial product purchases and testing.

In case you don't want to read ahead, here are MY conclusions:
* Napa Floor Dry is the most cost effective solution and offered an even distribution of particle sizes from 1/8 to 1/16.
* Turface by far has the largest amount of waste compared to the other products.
* Turface has 3x as many smaller particles (1/16 to 3/32) than larger ones (1/8+).

Disclaimers: These numbers are largely influenced by my insect screen (fiberglass) and how I sift. If you sift longer, you'll remove more waste. The waste calculation by weight is based on stated weight, which I did not confirm prior to sifting. By volume also does not reflect settling. Also, the volume numbers are rough estimates and the cost figures are obviously local. Al/Tapla has also experienced varied Turface waste by bag batch.

I took these measurements to compare waste between 4 of the water retention products recommended. Waste calculations by volume will never resemble ones based on weight. Dust/fines are the heaviest part of the product where measurement by weight could be triple the volume. But I believe they are helpful when comparing against each other, which was my goal.

        MEASUREMENTS OF WASTE BY WEIGHT  

           1/8+    1/16-  Usable  Waste*  Stated  Est.

PRODUCT            3/32   Product         Weight  Waste

==========================================================

Axis       10.75   10.50  21.25   3.75    25      15%

Playball   11.50   13.00  24.50   0.50    25       2%       

Floor Dry  14.75   16.25  30.50   2.75    --      ~8%  <--two bags=12gals

Turface    10.25   31.00  41.25   8.75    50      18%

All amounts were weighed and recorded. Afterward, they were re-weighed and recorded separately and then checked against the first recording for accuracy. Discrepancies were negligible.

I simultaneously double-sift, the top screen is a 1/8th hardware cloth, the bottom screen is fiberglass insect screen -- it appears 1/16th x 1/32th. What remains above 1/8th is the largest of the particles, what remains above the insect screen is the small to medium size. What falls through both is the waste/dust i.e. definitely smaller than 1/32 (which is the key size to avoid PWT). The calculations in the first table were performed by weight -- not volume. I used a typical home scale which obviously is not precise especially when measuring < 0.5 lbs.

Even though I never measured by volume (wish I had), I did take basic measurements (filled up the same #5 containers and took pictures). After reviewing the photos, here are very rough estimates of usable volume after my sifting.

         VERY ROUGH ESTIMATES OF WASTE BY VOLUME

           1/8+    1/16-  Usable   Stated   Est.     

PRODUCT            3/32   Product  Vol      Waste 

==========================================================

Axis       3.4     3.5     6.9     7.45     7.4%

Playball   3.8     3.6     7.4     7.45     0.7%

Floor Dry  5.9     5.9    11.8    12.00     1.7%

Turface    1.7     6.9     8.6    10.43     17.6%

Glancing at MY cost and MY usable product for the above measurements, here is my basic cost per gallon.

PRODUCT    Usable   My Cost    $/Usable G

==========================================================

Axis          6.9    $17*        $2.46

Playball      7.4    $14*        $1.89

Floor Dry    11.8    $13         $1.10

Turface       8.6    $12         $1.40

Hope it is useful to someone other than me.
-- Chris

* Napa Floor Dry is the most cost effective solution and offered an even distribution of particle sizes from 1/8 to 1/16.
* Turface by far has the largest amount of waste compared to the other products.
* Despite the waste, Turface is still the 2nd most cost effective solution (25% more than FloorDry) -- however, it requires the most sifting (labor).
* Playball, although 70% more expensive than FloorDry, requires the least amount of labor (or none at all) to sift. You should spot verify your bags however, as they may have more fines for a variety of reasons.
* Turface has 3x as many smaller particles (1/16 to 3/32) than larger ones (1/8+). Those in desert regions may appreciate this factor and sift with fiberglass screen.

My recommendation is the Napa Floor Dry. Though due to my climate and application, I still buy an equal amount of Turface as Floor Dry.

Other Benefits: Napa Floor Dry bags are half the size for half the cost of Turface, so they are easier for smaller batches. They are also the only bags to have handles on them. Al/Tapla has stated that Floor Dry (Calcined DE products) are a bit more water and CEC retentive than Turface. I have used all the above for a year now and have not seen the "mud" degradation experienced by some using Oil-Dri products.

Also, because of the small amount of waste and even distribution of particle sizes, a huge benefit is scooping directly from the bag. In order to force the smallest fines down to the bottom of the bag, use the handle to hold the bag vertically and shake it. Then jostle it around the sides, again keeping it vertical. Finally, store the bag standing upright. This makes it easy for those less critical situations, wherein you can easily scoop Floor Dry directly and not take the time to sift. In no situations have I scooped into the lowest 25% of the bag however. When important, I always sift the entire bag and recommend the same.

Lastly, this thread didn't discuss the various product sources and types. But Napa Floor Dry is mined by EP Minerals which also produces Axis and Playball. As can be seen in this links: Floor Dry and Axis are nearly identical in appearance.

Example Photo of Wet Products

-- Chris
I am not a representative of, nor affiliated with, any of the products named above and in no way benefit from, nor warrant suitability of, their use.