DE Filter Q...

[RASelkirk]

Hi all,

Anyone got a "conversion rate" for converting the DE requirement by weight to something more user-friendly, like cups or quarts?

I have a Hayward 3620 which requires 4 1/2 lbs per backflush, I've been using 4 1/2 two-quart measuring "units" for years and am now not sure this is enough. After 10 years, I fear a busted grid has got me...

BTW, I usually backflush 2x's a year (full clean 1x) and even then, the pressure never goes more than 2 or 3 lbs over my fresh gauge!

TIA!

Russ

 

[jblizzle]

Best to just get a scale and measure what your container holds. Note that the "one pound" scoops that they sell rarely hold 1 pound

- - - Updated - - -

Also note that after a backwash only, we suggest adding about 80% of the typical full DE amount that would be needed after a full tear down.

 

[RASelkirk]

Yup, I could do that and probably will despite the mess. Do people with DE filters really measure their dose with a weight scale?

Russ

 

[jblizzle]

I did once to find out what my container really held and then knew how many scoops to use.

I now use a large bucket and weighed the DE in it once to find the level to fill it to in the future. Then just make a slurry in the bucket before pouring it in.

I do not really worry too much about being that accurate

 

[JamesW]

DE has a bulk density of about 20 pounds per cubic foot. 4.8 pounds of DE will have a volume of about 0.24 cubic feet (230 fluid ounces, 7.18 quarts or 1.8 gallons).

4 pounds = about 24 cups.

Also, note that most pool stores sell a 1 pound DE scoop (about 48 ounces).

 

[jblizzle]

Also, note that most pool stores sell a 1 pound DE scoop (about 48 ounces).

True, but have you ever weighed what they really hold? IIRC mine held about 0.8 pounds. You would have to really pack it in to get up to 1 pound.

 

[JamesW]

I haven't verified that the scoop is accurate. I will check when I get a chance.

 

[RASelkirk]

Thanks for the input!

Russ

 

[RASelkirk]

OK, I weighed my full 2-QT measure and got 280 grams (423 full - 143 empty) which works out to only 0.6 lbs. So, for the 4.5 lbs required, I'll need to use 7 full measures plus a cup. I had been using only 4.5 measures, a little more than half the req'd amount...

Russ

 

[JamesW]

64 ounces weighed 0.6 pounds?

 

[RASelkirk]

64 ounces weighed 0.6 pounds?

Ounces by volume is not the same as ounces by weight. This is a liquid volume measure I'm using, top it off with DE and it weighs 0.6#. If one were to weigh it full of water instead, it would be ~ 4.2 lbs...

Russ

 

[JamesW]

Yes, I understand about ounces volume. I was surprised that 64 fluid ounces only came to 0.6 lbs.

I have a Hayward de cup that is supposed to be 1 lb of de and it's about 48 ounces.

I have a 25 lb bag of de. I will transfer the de from the bag to a container with the scoop to see how many scoops it takes.

 

[RASelkirk]

Me too, I was way underfilling my system! I should have realized, a 25# bag by 4.5# per fill should be around 6 fills. Seems like I was getting more like 10 per bag. I've used some of this bag, but have another unopened one that I can check using your scoop suggestion...

Russ

 

[JamesW]

I got about 25 scoops from a 25 lb bag. I did it twice and got 23.5 scoops then 26 scoops.

 

[jblizzle]

Does the bag actual weigh 25 pounds?

Perhaps your scoops is better than mine

 

[JamesW]

I didn't weigh the bag. But it did say 25 lbs. I assume that it's probably accurate.

My scoop is about 48 oz. What volume is yours?

 

[jblizzle]

No idea, have not used it in years. I just pour into a 3 gallon bucket up to a certain level that I have previously weighed (and honestly, that still makes it sound like I pay more attention than I do )

 

[RASelkirk]

I got about 25 scoops from a 25 lb bag. I did it twice and got 23.5 scoops then 26 scoops.

See, I must have weighed my scoop at one time! Only way I could have come up with 4 1/2 scoops equaling 4 1/2 lbs. I do know the stuff I have now, 25# in a plastic sack, is prolly different than the stuff I bought before, 25# in a heavy paper sack. Is all DE the same? When I get back from vacation mid-October, I plan on a full disassemble and clean. I'll weigh out my unopened sack then...

BTW, the salt gen and DE filter are by far the best investments I've made to our pool. I can't remember the last time I put algaecide in, or any other "fix" for that matter!

Russ

 

[jblizzle]

Algaecide is almost never recommended. And the filter does not prevent algae. The key is to just maintain the correct FC level for your CYA level according to the [FC/CYA][/FC/CYA].

All pool DE should be the same.

 

[RASelkirk]

Algaecide is almost never recommended. And the filter does not prevent algae. The key is to just maintain the correct FC level for your CYA level according to the [FC/CYA][/FC/CYA].

All pool DE should be the same.

Thought so.

While DE may not prevent algae, it sure does filter it better! Eight microns vs. forty, IIRC. Sand does a poor job, or did on our pool. Previously, with sand and a chlorinator, I spent $500 to a grand a year trying to keep it clean. Algae was a constant battle as well as the chlorine destroying everything in our pool room. Now, I buy a sack of DE and maybe 8 sacks of salt per year and no corrosive fumes...

Russ