Does Muriatic acid dissolve lanthanum phosphate clogged in filter cartridge?

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david8753

Member
Sep 5, 2023
17
Citrus Heights, CA
Pool Size
25000
Surface
Plaster
Chlorine
Liquid Chlorine
Hey folks,

So I, like an idiot, put phosphate remover in my pool because my phosphates were incredibly high (3000+ ppb).

This clouded the water, as expected, and I cleaned my filter cartridges everyday for the last couple of days.

I noticed today that my filter pressure was still +10 psi higher than it should be, even after cleaning. After removing the cartridges and running the pump on its own the PSI went back down to the normal level it should be...meaning that my cartridges are clogged AF with lanthanum phosphate.

The filters are basically brand new (installed them 5 months ago). They still look like they just came out of the box, but when I look into the pleats I can see that there is a ton of lanthanum phosphate right in the inner most part of the pleats that my hose cannot seem to wash out.

I am soaking them in 1:20 muriatic acid for 2 hours to see if this clears the issue, but it got me wondering:

Is the 1:20 muriatic acid treatment going to help out?
Is there some other chemical that will dissolve these stuff that is safe to use?
Perhaps a different procedure that I can do to remove this stuff?

Or are my cartridges just ruined and I need to get new ones?
 
It’s worth a try but my guess is that it’s not going to help much.

Which phosphate remover product did you add?

PR’s are basically an acidified solution of lanthanum chloride. The chloride salt, at low pH, is highly soluble and stable. When added to pool water the lanthanum reacts first with carbonate and then converts to a phosphate. This is why you typically wait 24-36 hours while the lanthanum is being cleared by the filter.

I’ve never heard of a lanthanum product not being compatible with all filters types so that’s why I’m interested in what exactly you added.
 
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The Orenda product on its own should not have clogged the filter media like that. It’s very strange.

perhaps you had some co-precipitation of calcium scale as well.

What are you test results showing? Is your CSI routinely negative?
 
My CSI is a bit low at the moment because I just finished doing a zero alkalinity acid treatment to get all the copper out of my pool (was at 1.6 ppm, now its at 0.15 ppm). I did a 50% dilution + CuLator to achieve this reduction so i'm thinking that it could just be because the water is adjusting back to normal. Here are my test results:

PH - 7.0 (and rising via aeration, target is 7.3 so I can check one last time for free copper before shocking)
TA - 95
FC - 4
CC - 0 - 0.5
CYA - 55
CH - 159 (Its low right now due to the dilution, but I have a plaster pool and will use calhypo shock once i can confirm copper levels are still below 0.2ppm before shocking....so it will go up after that)

Taking all of that into consideration: Yes, my CSI at the moment is -0.7 so it is corrosive but once the PH gets within range then that won't be an issue anymore. Normally its within range so this is just a temporary thing (You think it could be plaster that is floating around in there?)

The spike in phosphates was from using a metal sequestrant during the Zero Alkalinity Acid Treatment, but then I confirmed with CuLator that the only way metals can be captured is if they are free so I was trying to let that treatment break down so I can free up the Copper for capture (Hence my thought that PR-10000 would sort of kill two birds with one stone)

I took my water to Leslie's for testing because customer service told me that their AccuBlue machine do total copper...but I don't think thats actually true (Anyone know about that?)
To be even more clear here: The test results I showed above are from my own Taylor kit...not the pool store...I don't trust those guys

I'm guessing that the best move here is to SLAM to get everything stable again....but obviously I don't want to do that unless I can be fairly certain that my copper levels are below 0.2 ppm
 
Sorry, to be clear: The CH test is from the pool store (I don't have a CH test kit)
TA i am estimating because the Taylor test kit sorta went slightly less green at 9 drops and it went red after the 10th so I am just approximating that
 
Just be sure you are using accurate data. Pool store CH tests can be wildly off. As their TA results can be.

Hard to have a pH of 7 with a TA over 100.
 

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mknauss said:
Just be sure you are using accurate data. Pool store CH tests can be wildly off. As their TA results can be.

Hard to have a pH of 7 with a TA over 100.
Click to expand...
Oh interesting about the CH + TA test

I can confirm that my pH and TA tests are correct using the Taylor Kit. I'm sure this means my PH is gonna go up fairly quickly
 
What Taylor test kit are you using?

For the TA and CH tests - continue to add drops until the color no longer changes. Then subtract the last drop that didn't change the color.
For the TA test - 9 drops still green and 10 drops red doesn't necessarily mean the test is completed.

Fill out your signature with pool, pool equipment (including manufacturers and model numbers) and test kit info.
This assists us in providing you help specific to your pool without the need to ask each time.
 
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