Food grade DE in sand filter to treat pollen issue made matters worse

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J

jacko

Member
Sep 11, 2023
13
mid-Atlantic
Greetings.
I have had a persistent issue over the last few weeks which I have attributed to pollen, dust or dead algae based on information on this site (example: What is this brownish dust at the bottom of my clear pool? ). An extremely fine yellow-brown dust accumulates in the crevices of my vinyl liner, it does not adhere to walls, it shows no preference to sun or shade, and it does not proliferate in isolation. It also does not respond to shock treatment (my CC readings are zero both before and during shock). The sand filter is too coarse to extract this substance, and so the problem continues to worsen, as additional pollen accumulates on a daily basis, and anything I brush up simply goes through the filter and back out the jets.

I followed the directions of this article: Add DE to a Sand Filter , and paying no attention to the last line, slowly and incrementally added 3.5 cups FOOD-GRADE DE into my skimmer (which I had on hand). Noticing very little filter pressure change, I figured I'd better stop there and reevaluate. My problem got worse of course, because the DE went straight through the filter and made the pool significantly cloudier than before. So I now have at least two substances that my sand filter will not pick up.

I surmised that perhaps there's more difference in food-grade vs. pool-grade DE than simply the level of purity. I discovered other pool owners having made the same mistake that I did; e.g., Added food grade DE to sand filter .

It's my fault for not reading the last paragraph of the article critically. I'm aware that DE is an irritant and carcinogen, and skimmed over what seemed to be a cautionary note on handling the substance. The final sentence states "Gardening DE, while safer to handle, has not been heat treated and therefore is not suitable for use in pool filters". Firstly, "not suitable" (tucked at the end of the article) really doesn't capture the gravity of the situation. Secondly, there's no mention of "food grade" at all. Perhaps these are the same? I suggest amending the article to clearly delineate why it's "not suitable" in order to save future pool owners from similar anguish, a simple warning within the stepwise instructions themselves, perhaps.
Apologies for the long-winded drivel.

Anyway, I hesitate to ask, but: should I go out and buy some pool grade DE to try to get rid of the food grade DE?? And the pollen of course! It feels like the old lady who swallowed a spider to catch a fly...
Any other thoughts appreciated.
Thanks for reading.
 
Whoa Jacko....sorry to read of this mishap. I didnt realize it was still pollen season? Are you sure its not algae? Dead and dying algae looks like greyish brown dust too.

The best advice I can offer is to backwash your sand filter (in case any still remains in there). You may need to do a deep clean of the filter also.

I would also obtain some skimmer socks for your skimmer(s). Use one to line the inside of the skimmer and see if it captures some.

Can you vacuum to waste, to get as much out as you can? I would go slow. Then top off the water to replace lost water.

What I can't answer is whether or not adding the *proper* DE to the sand filter now would capture the food DE?

Maddie :flower:
 
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YippeeSkippy said:
Whoa Jacko....sorry to read of this mishap. I didnt realize it was still pollen season? Are you sure its not algae? Dead and dying algae looks like greyish brown dust too.

The best advice I can offer is to backwash your sand filter (in case any still remains in there). You may need to do a deep clean of the filter also.

I would also obtain some skimmer socks for your skimmer(s). Use one to line the inside of the skimmer and see if it captures some.

Can you vacuum to waste, to get as much out as you can? I would go slow. Then top off the water to replace lost water.

What I can't answer is whether or not adding the *proper* DE to the sand filter now would capture the food DE?

Maddie :flower:
Click to expand...
Well, no idea if it's pollen, dust, dead algae. It just exhibits the same mysterious "dusty" behavior as stated in other similar threads. It's the first year I've had this problem, out of four years with the pool. I meant to ask about skimmer socks too. I will try that. I did install a vacuum-to-waste line last year when switching to salt (thanks to this site). I'm hesitant about that since the stuff settles everywhere and is so fine that any movement of water causes it to dissipate. I'd have to cover every inch of the pool with the vacuum and hope it was getting sucked up rather than dispersed. I will try that if I have to, after the skimmer socks and maybe after the pool-grade DE. Thanks for the additional links!
 
Ummm, I will be probably roasted alive for this, but you may want to read up on the use of floc in this instance. Its use is pretty frowned on here. Floc, not any of the "clarifiers". Some pool stores sell generic Alum, which is cheaper and works as well as the named brands. DO NOT run your filter when using, set it on bypass. Mix, add, circulate for a few hours. Turn everything off and wait. At least a day. Two is better. Gray clumps will settle deeply all over the bottom. Slowly and carefully vac to waste. Moving too fast will break it up, and cause everything to resuspend. You WILL go through a LOT of water. I would typically vac until it got almost too low for the skimmers. Then wait for the garden hose to refill above the skimmer tops, and then go at the vac again. Once you get to the point where it is no longer accumulating on the bottom (yes, it may do more after the first vac), you can restart your filter, and start the process of rebalancing everything, starting with a SLAM. Heavy amounts can plug your sand to the point of needing to replace it, hence never running your filter while it is noticeably coagulating stuff to the bottom.

It will, however, grab all the pollen, dead algae, DE and the like suspended in the water, and drop it out. I used to use a lot before I took out the mammoth white pines that were next to the pool. Or when the dead algae load was way too much for the undersized sand filter, which tended to blow it all back into the pool.

There were older threads about buying large 1 micron filter bags, that went on the outlets, to capture suspended particles. I tried those too - they helped a tiny bit, but not a lot....

My pool life changed this year when my sand filter broke, and I changed up to a properly sized cartridge filter...
 
sande005 said:
Ummm, I will be probably roasted alive for this, but you may want to read up on the use of floc in this instance. Its use is pretty frowned on here. Floc, not any of the "clarifiers". Some pool stores sell generic Alum, which is cheaper and works as well as the named brands. DO NOT run your filter when using, set it on bypass. Mix, add, circulate for a few hours. Turn everything off and wait. At least a day. Two is better. Gray clumps will settle deeply all over the bottom. Slowly and carefully vac to waste. Moving too fast will break it up, and cause everything to resuspend. You WILL go through a LOT of water. I would typically vac until it got almost too low for the skimmers. Then wait for the garden hose to refill above the skimmer tops, and then go at the vac again. Once you get to the point where it is no longer accumulating on the bottom (yes, it may do more after the first vac), you can restart your filter, and start the process of rebalancing everything, starting with a SLAM. Heavy amounts can plug your sand to the point of needing to replace it, hence never running your filter while it is noticeably coagulating stuff to the bottom.

It will, however, grab all the pollen, dead algae, DE and the like suspended in the water, and drop it out. I used to use a lot before I took out the mammoth white pines that were next to the pool. Or when the dead algae load was way too much for the undersized sand filter, which tended to blow it all back into the pool.

There were older threads about buying large 1 micron filter bags, that went on the outlets, to capture suspended particles. I tried those too - they helped a tiny bit, but not a lot....

My pool life changed this year when my sand filter broke, and I changed up to a properly sized cartridge filter...
Click to expand...
Thank you for the suggestion. I know from my reading that floc is highly discouraged here. I hope it doesn't come to that. Unfortunately, I do not have a way currently to bypass the filter while still circulating the water. I have a slide valve and had to install my own vacuum-to-waste line last year. So I'd have to do some more plumbing first, which makes the prospect even less appealing. I'm going to turn my system off for a while and hope the DE settles enough to carefully vacuum to waste. If that doesn't work, I may try pool DE to catch the food DE. I'm assuming that if I don't clear it up this season, it will have all settled out by next spring's opening, where I should be able to vacuum more effectively.
 
jacko said:
Greetings.
I have had a persistent issue over the last few weeks which I have attributed to pollen, dust or dead algae based on information on this site (example: What is this brownish dust at the bottom of my clear pool? ). An extremely fine yellow-brown dust accumulates in the crevices of my vinyl liner, it does not adhere to walls, it shows no preference to sun or shade, and it does not proliferate in isolation. It also does not respond to shock treatment (my CC readings are zero both before and during shock). The sand filter is too coarse to extract this substance, and so the problem continues to worsen, as additional pollen accumulates on a daily basis, and anything I brush up simply goes through the filter and back out the jets.

I followed the directions of this article: Add DE to a Sand Filter , and paying no attention to the last line, slowly and incrementally added 3.5 cups FOOD-GRADE DE into my skimmer (which I had on hand). Noticing very little filter pressure change, I figured I'd better stop there and reevaluate. My problem got worse of course, because the DE went straight through the filter and made the pool significantly cloudier than before. So I now have at least two substances that my sand filter will not pick up.

I surmised that perhaps there's more difference in food-grade vs. pool-grade DE than simply the level of purity. I discovered other pool owners having made the same mistake that I did; e.g., Added food grade DE to sand filter .

It's my fault for not reading the last paragraph of the article critically. I'm aware that DE is an irritant and carcinogen, and skimmed over what seemed to be a cautionary note on handling the substance. The final sentence states "Gardening DE, while safer to handle, has not been heat treated and therefore is not suitable for use in pool filters". Firstly, "not suitable" (tucked at the end of the article) really doesn't capture the gravity of the situation. Secondly, there's no mention of "food grade" at all. Perhaps these are the same? I suggest amending the article to clearly delineate why it's "not suitable" in order to save future pool owners from similar anguish, a simple warning within the stepwise instructions themselves, perhaps.
Apologies for the long-winded drivel.

Anyway, I hesitate to ask, but: should I go out and buy some pool grade DE to try to get rid of the food grade DE?? And the pollen of course! It feels like the old lady who swallowed a spider to catch a fly...
Any other thoughts appreciated.
Thanks for reading.
Click to expand...
The fact that the pool school article does not explicitly state that food grade DE should NEVER be put into a pool was brought up at least three years ago Diatomaceous Earth, To Eat or Not To Eat, That Should Be Stated! .

> "I love this site, but Somebody really needs to put this information in with the How To page about adding DE."
> "Noted -- we can expand the warning in the DE article."

Please, to whomever has the power to do so, please revise the article to warn people specifically not to use food grade DE in pools because it goes straight through the filter and compounds any issues that pool owners were trying to solve.
 
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jacko said:
The fact that the pool school article does not explicitly state that food grade DE should NEVER be put into a pool was brought up at least three years ago Diatomaceous Earth, To Eat or Not To Eat, That Should Be Stated! .

> "I love this site, but Somebody really needs to put this information in with the How To page about adding DE."
> "Noted -- we can expand the warning in the DE article."

Please, to whomever has the power to do so, please revise the article to warn people specifically not to use food grade DE in pools because it goes straight through the filter and compounds any issues that pool owners were trying to solve.
Click to expand...
Earlier this year: Food grade Diatomaceous Earth "Might be something good to add to that blog page. Add DE to a Sand Filter "
Back in 2013: Food grade Diatomaceous Earth "Funny you should mention this, we just had a member try it out and taught us the lesson he learned the hard way."
This is an age-old issue that has been screwing up people's pools for, I'm assuming, well over a decade. A great deal of headache could be avoided by adding a few words to the pool school article.
 
jacko said:
Please, to whomever has the power to do so, please revise the article to warn people specifically not to use food grade DE in pools because it goes straight through the filter and compounds any issues that pool owners were trying to solve.
Click to expand...

jacko said:
This is an age-old issue that has been screwing up people's pools for, I'm assuming, well over a decade. A great deal of headache could be avoided by adding a few words to the pool school
Click to expand...
It's been forwarded up the chain. Thanks for the suggestion. :)
 
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jacko said:
Earlier this year: Food grade Diatomaceous Earth "Might be something good to add to that blog page. Add DE to a Sand Filter "
Back in 2013: Food grade Diatomaceous Earth "Funny you should mention this, we just had a member try it out and taught us the lesson he learned the hard way."
This is an age-old issue that has been screwing up people's pools for, I'm assuming, well over a decade. A great deal of headache could be avoided by adding a few words to the pool school article.
Click to expand...
I would avoid the DE altogether. If the sand filter is at least reasonably sized and not channeled it should keep the pool very clear. There’s lots of winners of the TFP clear pool challenge with sand filters,
 
Jacko doesn't list his equipment. But another thought -
In my case, the old sand filter was undersized for the pool and the pump horsepower. So at higher speeds, the dirt was literally being forced out of the sand and back into the pool. I noticed it most after I had vac'd up a heavier amount of pollen/algae, and could see it coming out of the returns. Then I would heavily backwash, and try to finish the job. Then let it settle for a day or two, and repeat. After up to a week, I would finally get it all under control.
It MIGHT help to turn down the speed of the pump, if you can, when using the vac. Yes, you have to go slower/much slower. But you may avoid blowing quite as much back into the pool as one might at higher speeds. Doing a deep clean of the sand also helped me a lot in my never ending war....
 
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sande005 said:
Jacko doesn't list his equipment. But another thought -
In my case, the old sand filter was undersized for the pool and the pump horsepower. So at higher speeds, the dirt was literally being forced out of the sand and back into the pool. I noticed it most after I had vac'd up a heavier amount of pollen/algae, and could see it coming out of the returns. Then I would heavily backwash, and try to finish the job. Then let it settle for a day or two, and repeat. After up to a week, I would finally get it all under control.
It MIGHT help to turn down the speed of the pump, if you can, when using the vac. Yes, you have to go slower/much slower. But you may avoid blowing quite as much back into the pool as one might at higher speeds. Doing a deep clean of the sand also helped me a lot in my never ending war....
Click to expand...
Sand filters work much better at lower speeds.
 
sande005 said:
Jacko doesn't list his equipment. But another thought -
In my case, the old sand filter was undersized for the pool and the pump horsepower. So at higher speeds, the dirt was literally being forced out of the sand and back into the pool. I noticed it most after I had vac'd up a heavier amount of pollen/algae, and could see it coming out of the returns. Then I would heavily backwash, and try to finish the job. Then let it settle for a day or two, and repeat. After up to a week, I would finally get it all under control.
It MIGHT help to turn down the speed of the pump, if you can, when using the vac. Yes, you have to go slower/much slower. But you may avoid blowing quite as much back into the pool as one might at higher speeds. Doing a deep clean of the sand also helped me a lot in my never ending war....
Click to expand...
That's the plan, slow and steady. My pump has been off for a day. The shallow end looks reasonable but the main drain is faint. The food grade DE does settle slowly, as evinced in my tabletop experiment, but the pool's a bit bigger than my jar so I have no idea how long this might take. A lot of work to extract 3.5 cups DE out of 22k gallons. Also, I was planning to vacuum to waste. If this doesn't work well, I will try circulating regularly with the pump speed way down and intermittent backwashing. For what it's worth, I believe my sand filter is suitably sized (Triton TR100C) and I did replace the sand last year when I switched over to salt, so the edges should still be "sharp".
 
If really desperate...Home - The Slime Bag

Some very old threads here about them. As noted earlier, I made a DIY version using diesel filtering bags (old threads about how-to somewhere on this site). They did filter out junk, but not all that effective. And the bags are very hard to clean afterwards. Saved one, and it does work perfectly to add to a return, and use it instead of a sock to add CYA, though....
 
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jacko said:
warn people specifically not to use food grade DE in pools because it goes straight through the filter and compounds any issues that pool owners were trying to solve.
Click to expand...
Isn't food grade DE WAY MORE expensive than DE for pools?

I'm curious which food grade DE you purchased?

As a datapoint, I purchased 50lb of DE for pools for $35 via eBay
 
plnewb said:
Isn't food grade DE WAY MORE expensive than DE for pools?

I'm curious which food grade DE you purchased?

As a datapoint, I purchased 50lb of DE for pools for $35 via eBay
Click to expand...
Food grade de at the co op is cheap. I have used it to get rid of ants. It was many years ago though so really everything was “cheap” compared to now 😁
 
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