Orenda PR-10000 versus cheap Lanthanum Chloride salt crystal

[rock]

From the MSDS, the Orenda PR-10000 phosphate remover appears to primarily contain lanthanum chloride

Hi Richard,
Looking for a cheap bulk source of Lanthanum Chloride salt crystals, do you have any idea what the gram dosage of LaCl³ is from a typical does of PR-10000?

Wikipedia confirms LaCl³ is used to precipitate phosphates from solutions:
http://en.wikipedia.org/wiki/Lanthanum% ... 9_chloride

The MSDS for Lanthanum Chloride gives the CAS number as Lanthanum chloride 10099-58-8:
http://www.sciencelab.com/msds.php?msdsId=9924457

Googling, it's about a dollar a gram for the reagent grade anhydrous LaCl3:
http://www.ebay.com/itm/Lanthanum-Chlor ... 1262714936

But, I'd like to find a vastly cheaper bulk supplier of (less pure perhaps) Lanthanum salts, but, first, the quantity-needed question is:
Q: What is the dosage (in grams of Lanthanum Chloride) in PR-10000?

 

[JasonLion]

Re: Orenda PR-10000

From what I can see, they don't say enough to figure that out.

Phosphate removers normally contain both lanthanum chloride and a clarifier, so it wouldn't be anything close to 100% lanthanum chloride.

 

[chem geek]

Re: Orenda PR-10000

I wrote about this product in the thread Orenda Technologies PR-10000 and CV-700 Products. You can roughly determine the amount of lanthanum chloride based on the dosage which is that one quart will remove 10,000 ppb phosphates in 10,000 gallons. Since 10,000 gallons is 37,854 liters and 10,000 ppb phosphate is 10,000 µg/L of phosphate (PO₂^3-) with a molecular weight of 95 g/mole, this is (10000 µg/L) * (37854 liters) / (1000000 µg/g) / (95 g/mole) = 3.985 moles. So that is how much lanthanum is required. Lanthanum chloride has a molecular weight of 245.26 g/mole so that means (3.985 moles) * (245.26 g/mole) = 977 grams of lanthanum chloride in one quart of PR-10000.

One quart of water weighs about 946 grams and note that from the MSDS the specific gravity of the product is 1.47 g/ml. So this implies a very concentrated product with the 977 grams in one quart (0.946 liters) so (1.47 g/ml) * (946 ml) = 1391 grams so that implies 1391-977 = 414 grams of water and 70% concentration (by weight) of lanthanum chloride in the PR-10000 product. Lanthanum chloride is extremely soluble in water and forms hydrates. Sodium chloride salt has solubility in water of 359 g/L while lanthanum chloride apparently has solubility of at least 977 g / 0.946 liters = 1033 g/L. Note also that the PR-10000 product is low in pH, probably because lanthanum hydroxide is insoluble in water so having a low pH (probably from added hydrochloric acid) prevents the formation of that precipitate.

I don't believe the PR-10000 contains any clarifier since it severely clouded my pool during the experiment. Products like PhosFree have clarifier which is why they are 7-13% for regular strength and 15-40% for commercial strength.

 

[rock]

Re: Orenda PR-10000

70% concentration (by weight) of lanthanum chloride in the PR-10000 product ... added hydrochloric acid ... I don't believe the PR-10000 contains any clarifier

Hi Richard & Jason,
Thanks for taking the time to separate (Jason) and answer the question (Richard).

I love how Chem Geek thinks, in that he long ago deduced Lanthanum Chloride was the key inorganic phosphate (orthophosphate) flocculating ingredient based on LaCl3 toxicity hints in the Orenda PR-10000 MSDS.

Even though my free chlorine (FC) is usually at least 7.5% above my cyanuric acid (CYA) level (I need to have it tested again though), when I brush the walls of my ~40K gallon pool (which is 60 feet long so there is a lot of wall) I can see a light coating of greenish-gray dust billow up lightly behind the wire brush at predictable spots. Not much, one or two brush strokes, and it's just a light cloud dispersing at the bottom of the pool but enough for me to wonder every day why the chlorine isn't doing the BBB thing. [Note: My PR2000 self-cleaning system needs the 9-port water valve heads rebuilt - so that isn't helping matters any. Unfortunately, I haven't ever done the chlorine demand test, which I need to do for more data.]

As a side note, well before I had read that the phosphates aren't the real problem - in the past - I had used cupric algaecides from Lowes - which, incidentally, stained the white calcium deposits covering the pool walls from my hard well water with a very lovely greenish-blue relatively even tinge - so - I learned, first hand, about side effects on almost anything poured in the pool - in this case, a fortuitous coloring of the otherwise-dark-gray walls.

Given the persistence of this light algae covering, which I've tentatively attributed to three key factors (micro-sheltering on the calcium-coated walls, and a ready source of clearly visible green algae in a pond only a hundred feet upwind, coupled with Silicon Valley sunlight all day like you can't believe as there is no shade in sight), I'm going to have the phosphates tested at Leslies but they're generally high enough that the pool stores predictably try to sell me on their magic miracle cures. As always, my gut reaction is to look at the ingredients, and, as is typical with the miracle cures, they don't say. So, it was with glee that I found Chem Geek's threads explaining how the Orenda PR-10000 worked (LaCl3 apparently precipitates the inorganic orthophosphates into Lanthanum Phosphate, which is then filtered out by the filtering system).

Reading the reference from Richard above, I'm impressed even he, the Chem Geek Logic Meister, brought his 3,000 ppb orthophosphate level down to 5% of that in his tests of the product.

Intrigued about running my own test, I googled and found various Lanthanum Chloride solutions & reagent grade Lanthanum Chloride, & anhydrous Lanthanum chloride heptahydrates - and I started wondering how much of those one would put in a pool (per 10,000 gallons) so that I could calculate effective costs comparisons of Lanthanum Chloride versus the pool-store PR-10000 solution (which Chem Geek kindly calculated to be roughly around $3 for every 1,000 ppb in 10,000 gallons).

Given Richard fleshed out the PR-10000 economics, at this point, I guess my goal is to understand:
Q1: Does it matter which chemical-grade Lanthanum Chloride I buy for my experiment?
Q2: How much of that LaCl3 (solid or solution) should I use per 10,000 gallons for a 1,000 ppb flocculation?
Q3: How does that amount compare, in cost, to PR-10000 for the same effect?

one quart will remove 10,000 ppb phosphates in 10,000 gallons... = 3.985 moles, = 977 grams of lanthanum chloride in one quart of PR-10000

Assuming scalable calculations of a 10,000 gallon pool, and a simple 1,000 ppb reduction goal, does that mean that, if I buy the solid LaCl3 (at roughly $1/gram), it looks like it would take 1/10th of the 977 grams of LaCl3, or roughly 100 grams of Lanthanum Chloride, to reduce orthophosphates by 1,000 ppb?

If so, the cost of reagent-grade Lanthanum Chloride appears to be prohibitive, at about $100 to reduce a 10,000 gallon pool by 1,000 ppb phosphates (if I followed Richard's math properly).

 

[chem geek]

Re: Orenda PR-10000 versus Lanthanum Chloride for phosphate

The reagent grade materials are way too expensive. If you got the PR-10000 directly it's $31 per quart (that's about 3 cents per gram of lanthanum chloride) and you'd only use 1/10th of this bottle to lower phosphates by 1000 ppb in 10,000 gallons. And as I noted, it's more economical than PhosFree, BUT it does not have any clarifier so if you are impatient you'd have to factor in that cost though something like GLB® Clear Blue™ and BioGuard® improve™ polysheen® blue are both inexpensive and effective (you don't use very much).

Note that the only reason I used it was because the manufacturer came over to my house to do an experiment for free. It did make the pool less "reactive" if the chlorine level were to get too low, but the same could be said of the 50 ppm Borates that I added in some subsequent season.

 

[rock]

Re: Orenda PR-10000 versus Lanthanum Chloride for phosphate

The reagent grade materials are way too expensive.

I agree.

From a theoretical standpoint, Lanthanum Chloride is too expensive to use as a phosphate flocculant if the only other source on the web other than PR-10000 is reagent grade anhydrous LaCl3.

it's $31 per quart (that's about 3 cents per gram of lanthanum chloride).

How did you figure out how many grams of LaCL3 are in a quart of PR-10000?

 

[chem geek]

Re: Orenda PR-10000 versus Lanthanum Chloride for phosphate

I calculated the number of grams per quart based on the product dosage to lower the phosphate level as I calculated in this post earlier in this thread. Their product is one of the least expensive, but you may need to use a clarifier (those are inexpensive such as GLB Clear Blue or Bioguard Polysheen Blue).

If the algae is in areas of poor circulation, you might try getting rid of it by following the Slam process first and then orient your returns for better circulation, if possible. It's unusual to have green algae at the minimum to target FC/CYA levels unless circulation is poor.

 

[rock]

Re: Orenda PR-10000 versus Lanthanum Chloride for phosphate

you may need to use a clarifier

I had read about that in the prior posts but clarification is of no concern to me because I would simply live with a somewhat cloudy pool for the week or two that it might take the filter and self-cleaning system to collect all the flocculated phosphates.

If the algae is in areas of poor circulation

Yes, the algae is a light green daily dusting on the deeper walls, and around the corners. It probably doesn't help that the self-cleaning pop-up system isn't functioning at full pressure - but I'm debugging that separately.

I calculated the number of grams per quart based on the product dosage

Thanks for explaining, Richard.

My phosphates were measured yesterday at 500 ppb and Leslie's says a good number to aim for is below 100 ppb.
I'll assume this ratio is linear in our range of interest.

1 quart of PR-10000 contains 977 grams of lanthanum chloride which will remove 10,000 ppb phosphates in 10,000 gallons

I need to use that ratio to figure out how to calculate how many grams of LaCl3 would be needed to remove 400 ppb in 40K gallons.

Since removal of 10,000 ppb is two orders of magnitude too high for my situation, is this ratio reduction correct?
a. Roughly 1,000 grams of LaCl3 will remove 10,000 ppb phosphates in 10,000 gallons.
b. So, roughly 100 grams of LaCl3 will remove 1,000 ppb phosphates in 10,000 gallons
c. And, about 10 grams of LaCl3 should remove 100 ppb phosphates in 10,000 gallons

Given we buy LaCl3 by the gram, it seems the fundamental (1:10:10K) starting ratio might be:
d. 1 gram of LaCl3 should remove 10 ppb phosphates in 10,000 gallons

Now, applying that 1:10:10K ratio to my situation (I need to reduce by 400 ppb), does that mean:
e. About 40 grams of LaCl3 should remove 400 ppb phosphates in 10,000 gallons

So, for an approximately 40,000 gallon pool, is this linear (10:100:10K) assumption conclusion correct?
f. About 160 grams of LaCl3 should remove about 400 ppb phosphates in my roughly 40,000 gallon pool?

 

[chem geek]

Re: Orenda PR-10000 versus Lanthanum Chloride for phosphate

Your calculations are correct, though I think you are wasting your time and money going with the phosphate reduction approach since you don't know if you are properly maintaining the FC level in your pool since you are using store testing rather than your own TFTestkits TF-100 or Taylor K-2006 test kits, most especially a FAS-DPD test kit for an accurate FC level. With accurate info, you would SLAM the pool to kill off the algae before trying to maintain a normal FC/CYA level that never got below the minimum FC for the CYA level.

 

[rock]

Re: Orenda PR-10000 versus Lanthanum Chloride for phosphate

Your calculations are correct, though I think you are wasting your time and money going with the phosphate reduction approach

Hi Richard,
I don't disagree.
I'm not actually going with the phosphate reduction approach.

I read (and understood) all that you wrote - and - I believe that my 'real' problem is two-fold:
a) My CYA level is high and given my lack of a good testing approach, I was actually unwittingly low on chlorine (without realizing the implications)
b) There is a heavy source of algae within a few hundred feet of the pool (which may be inoculating it)

I also believe the solution is simple (albeit it takes understanding of the approach):
A) I need to maintain a FC:CYA ratio as per your chart
B) I need to SLAM the pool for now until I get it back under control

With all that having been said, it is still useful to know (from a scientific standpoint) how many grams of Lanthanum Chloride it would take to remove the high level of (inorganic) phosphates from my pool - and - how much that would cost if I were to buy bare bones LaCl3.

Thanks for the advice. Your help is much appreciated, and not wasted, as I will try to add value back by finding a supplier for anyone who needs it, for the Lanthanum Chloride, hopefully at something on the order of 1/10th the price of the PR-10000.

 

[chem geek]

Re: Orenda PR-10000 versus Lanthanum Chloride for phosphate

I never say never (that's a self-referential invalid statement, isn't it?) so if you do have algae reintroduced into your pool at a high rate and especially if it were yellow/mustard algae, then use of a supplemental algaecide approach might be reasonable, but that's a last resort after all the other more straightforward approaches are taken. So let's see how the standard SLAM and then proper FC/CYA maintenance works before trying something else.

 

[rock]

Re: Orenda PR-10000 versus Lanthanum Chloride for phosphate

let's see how the standard SLAM and then proper FC/CYA maintenance works before trying something else.

Agreed.

Meanwhile, we can possibly advance the knowledge of inexpensive SOURCES for reducing phosphates using Lanthanum Chloride (e.g., PR-10000) or Lanthanum Carbonate (e.g., PHOSfree).
Assuming a good metric might be the cost to reduce phosphates in 10,000 gallons by 100 ppb using either LaCL3 or La2(CO3)3

I'll see what I can calculate ... NOTE: UNFINISHED WORK IN PROGRESS!

1. Cost of PR-10000 (Lanthanum Chloride) to reduce phosphates by 100 ppb in 10,000 gallons:
Richard tells us in this thread that one quart of PR-10000 (i.e., 0.94635 liter) will remove 10,000 ppb phosphates in 10,000 gallons.
Let's round that quart out to 1 liter, which will remove 10,000 ppb in 10,000 gallons.
Therefore, 10 ml of PR-10000 should remove 100 ppb in 10,000 gallons.
Multiply the gallons by 4 (to 40,000 gallons) and multiply the phosphates by 4 (to 400 ppb) and my pool should take 4x4=16 times that 10ml or 160ml of PR-10000.
WIP Need to calculate the cost of 160ml of PR-10000.

3. Cost of the unmarketed metallic salt LaCL3:
Recommended dosage needed to reduce 10,000 gallons by 100 ppb = 10 grams.
WIP (I need to find a cheap supplier of Lanthanum Chloride salts.)

2. Cost of PHOSfree (Lanthanum Carbonate) to reduce phosphates by 100 ppb in 10,000 gallons:
Leslie's item #14105 PHOSfree, 2 liter $33 is ~$16.50/liter while Leslie's 14145PHOSfree, 3 liter $43 is ~$14.33/liter so, let's round that out to say PHOSfree is $15/liter.

WIP (I need to look up the recommended dosage needed to reduce 10,000 gallons by 100 ppb.)

4. Cost of the unmarketed metallic carbonate La2(CO3)3:
WIP (I need to look up the recommended mass needed to reduce 10,000 gallons by 100 ppb.)

WORK IN PROGRESS (I need to look up the dosage to bring 10,000 gallons down by 100 ppb for the products above.)

 

[chem geek]

Re: Orenda PR-10000 versus Lanthanum Chloride for phosphate

Look at the bottom of this post that I already linked you to earlier (do you look at those links?). I already compared pricing for the Orenda Technologies PR-10000 at $3.10 per 1000 ppb phosphate per 10,000 gallons by the quart or $2.45 by the gallon vs. PhosFree Commercial Strength at $6.67 vs. SeaKlear phosphate remover at $3.33 so the Orenda product was the least expensive. Now current pricing may be different, but I'll bet the relative pricing is similar.

I really don't see much point, though, since phosphate removers are hardly even needed. Even if one wants a supplemental algaecide, there are other approaches such as Polyquat 60 weekly or the use of 50 ppm Borates that can also be helpful and provide other benefits (Polyquat is a clarifier and the borates are a pH buffer and add some sparkle to the water by reducing surface tension).

 

[rock]

Re: Orenda PR-10000 versus Lanthanum Chloride for phosphate

I already compared pricing

Hi Richard,
I do try to look at, read, and understand ALL the links provided, but, I missed your calculations (in doing this, among many other things today). I apologize.
What I'm trying to figure out, from a theoretical standpoint, is the cost to me of reducing my phosphates from 400 ppb to 100 ppb in my 40K gallon pool so I can make my own assessment of the feasibility.

Starting with your numbers:
Orenda Technologies PR-10000 at $3.10 per 1000 ppb phosphate per 10,000 gallons:
I need to multiply the gallons by 4 (to get 40,000 gallons) and divide the 1,000 ppb by 2.5 (to get 400 ppb), which makes the cost, to me, of a single application only $3.10 * 4 / 2.5 = $5.
(Of course, I have to buy more than that - but that's the cost of a single application.)

Hmmm... that's about the cost of 1 gallon of HASA chlorine, which will raise the pool only 3 ppm chlorine.

Seems to me, IF IT WORKS, that it's a better deal than Chlorine, at those numbers.

EDIT: Calculating new numbers based on today's cost ...
Looks like 1 quart of Orenda PR-1000 is about $60
[attachment=0:k4lnm28z]orenda.png[/attachment:k4lnm28z]

Richard tells us in this thread that one quart of PR-10000 will remove 10,000 ppb phosphates in 10,000 gallons.
One quart is 32 ounces, so, at $60/quart, the Orenda PR-10000 today is about $2 per ounce (assume tax & shipping is, roughly, included).

I need to multiply the 10,000 gallons by 4 (to get 40,000 gallons) and to divide the 10,000 ppb by 25 (to remove only 400 ppb).
So, it will take 32 ounces ×4 ÷25 = about 5 ounces to remove 400 ppb from my pool.
That means it would cost me about 5 ounces x $2/ounce = $10 to remove 400 ppb from my pool in today's dollars.

For the first time, I have a realistic number that I can think about in order to compare against adding more chlorine at roughly $5/gallon.
Upon first inspection, the Lanthanum Chloride actually appears to be cost effective, compared to the price of shocking the pool, which, for me, is taking the pool from the target of 6 ppm to 20 ppm at about 1 ppm per 40 ounces of chlorine (or roughly 3ppm per gallon of chlorine).

So, just shocking once calls for 20 ppm - 6 ppm = 14 ppm of chlorine (which is about 5 gallons of chlorine, which is about $25).
Yet, removing the phosphates calls for about 5 ounces of PR-10000, which is about $10.

So, simply comparing the two options, side by side, it appears to be, upon initial inspection anyway, far cheaper to remove phosphates (about half the price) than it is to raise the chlorine level.
That is, if my math on top of your math is correct.

 

[chem geek]

Re: Orenda PR-10000 versus Lanthanum Chloride for phosphate

It isn't just about comparing cost. You are assuming that the phosphate remover will be effective. It will not remove organic phosphates at all. Algae can still grow using organic phosphate, though much more slowly, and if the chlorine gets so low as to have bacteria grow, then they can rapidly convert organic phosphates into orthophosphate (the type of phosphate algae use to grow more quickly and the type that phosphate removers remove). So you still need to make sure that you don't let the chlorine level get too low.

You also assume that you won't get more phosphates in the water. Some municipal water districts have phosphates in their water. I have 400 ppb phosphate in my tap water, for example. So this may not be a one-time dose. That's why I equate phosphate removers to be more like algaecides with some level of maintenance dose.

You said you wouldn't be using a clarifier, but the lanthanum phosphate and lanthanum carbonate that forms in the water doesn't filter very well so could take a while and you'll need to clean your cartridge filter when it does filter it out (perhaps with a clarifier). If you do get stuck, then figure the cost of GLB Clear Blue or BioGuard Polysheen Blue. You would use up to a quart for your sized pool if it was very cloudy so that's around $14.

Every pool is different and you could be lucky in yours that you don't have phosphates introduced at any great rate so that the cost of phosphate removal will be low. What you are really buying is insurance to make your pool less reactive to algae growth if the chlorine level gets too low. It's not necessary, but if you are unwilling or unable to measure levels with a proper test kit and maintain an appropriate FC/CYA level with decent pool circulation, then it might help, but with no guarantee.

 

[rock]

Re: Orenda PR-10000 versus Lanthanum Chloride for phosphate

You are assuming that the phosphate remover will be effective.

Hi Richard,
I was more trying to change the cost equation (by locating a dirt-cheap supplier of the base chemicals) than anything else.

From reading the TFP and googled references (some from the reef aquarium guys), I had already known the prevailing opinion for anyone wishing to aim for 100 ppb measurable phosphates (e.g., using the Taylor K-1106), where, we assume, somewhere around 125 ppb is the limiting level for algae.

It was always implied we can only test for and remove inorganic, i.e., orthophosphate (PO₄^3-) from the water (assuming they're the primary source of the phosphates), so, for the moment, we apparently ignore perhaps as many as five or more other more complex forms of phosphate that could be present and consumed by algae including ignoring other bioavailable organic compounds, such as nitrates - which - it may turn out, might be the real limiting factor in the end).

With those caveats, if we could find a (much) cheaper supplier of the base LaCl³, then we could change the cost equation and more easily lower the inorganic phosphate level to about 125 ppb, where, in theory anyway, algae should grow slower.

For this thread, I ignored the side effect of cloudy water from the lanthanum carbonate that is eventually filtered out and replaced with lanthanum phosphate. As you mention, it must also be assumed that maintenance doses may be needed, if for no other reason than to account for the additional phosphates released from oxidized algae (but chlorine also needs maintenance doses). And, algaecides are not being considered in this thread (where they too, suggest maintenance doses).

I've read the assessments of where phosphates come from, and, with my situation, there shouldn't be a lot of wind-blown farming soil, nor detergent contamination; so, my assumption was that the measured 500 ppb inorganic orthophophate was, probably, native in my well water (which is pumped up from 400 feet directly below ground from a well on my property). EDIT: I've emailed a request for a phosphate reading from my surrounding neighbors, all of whom have their own well.

To be clear, there was always the underlying TFP assumption that magic bullets don't exist; so, while bacteria seem to get by with far less phosphorous than algae, the chlorine goal is still to maintain the recommended target levels (for 50 ppm CYA) of 6 ppm (and shock at 20 ppm), so health risks should not be a problem whether or not I ultimately locate a non-reagent grade bulk LaCl³ supplier or not.

I understand, agree with, and subscribe to the primary concept at TFP that the goal is to maintain our swimming pools with the simplest, and least expensive, yet most logical methods; so I do realize the prevailing view that, as a sanitizer and algae preventer, chlorine (at $5 a gallon) fills that requirement better than rare earth metal salts do (at $240/gallon).

However, despite the prevailing view, I was mostly trying to understand whether I could radically improve the existing cost equation by (somehow) drastically lowering the price of the LaCl³ dose, probably by sourcing from bulk chemical supply house instead of from pool-supply outfits.

So, if this thread reverted back solely to the single goal of finding a dirt-cheap supply of lanthanum salts, it would serve the needs of many - because it could drastically change the cost equation.

NOTE: I do realize that, without drastically changing the cost equation, the prevailing TFP view is wholly logical and unassailable; I just had not seen in the TFP record, any concerted attempt to fundamentally lower the cost of sourcing the rare earth metal salts to well below that of the PR-10000 currently analyzed.

 

[chem geek]

Re: Orenda PR-10000 versus Lanthanum Chloride for phosphate

consumed by algae including ignoring other bioavailable organic compounds, such as nitrates - which - it may turn out, might be the real limiting factor in the end).

With those caveats, if we could find a (much) cheaper supplier of the base LaCl³, then we could change the cost equation and more easily lower the inorganic phosphate level to about 125 ppb, where, in theory anyway, algae should grow slower.
:
NOTE: I do realize that, without drastically changing the cost equation, the prevailing TFP view is wholly logical and unassailable; I just had not seen in the TFP record, any concerted attempt to fundamentally lower the cost of sourcing the rare earth metal salts to well below that of the PR-10000 currently analyzed.

Phosphates and nitrates are EACH limiting algae nutrients. So if you lower EITHER ONE of them to very low amounts, then you prevent algae growth. Nitrates are very difficult to lower so that is why phosphates are lowered instead. It is true that if there are higher nitrates then when phosphates rise you'll get faster algae growth (it's actually also related to the phosphate/nitrate ratio as well since not only absolute level but their relative amounts are also important for uptake). However, since nitrates are a byproduct of chlorine oxidation of nitrogenous organics (nitrogen gas is the primary product, but about 10-20% of the nitrogen becomes nitrate) there are usually plentiful nitrates and they are not the limiting nutrient.

As for the cost equation, there is your current situation which probably wouldn't have happened had you had your own proper test kit and maintained FC/CYA properly and possibly improved circulation. So the real question for pool owners who do what is practiced here at this forum is whether a product such as a phosphate remover saves them cost in the long run. For that to occur several things need to be true: 1) their level of phosphates needs to be somewhat low (500 ppb or lower; not 3000 ppb, for example) and needs to be introduced at a low rate, 2) they need to maintain a lower FC/CYA level to lose less and therefore use less chlorine and 3) they still need to make sure they don't get to a near-zero FC or else bacteria can convert organic phosphates to orthophosphates and an algae bloom with subsequent required shocking would still be needed. If you don't lower your FC/CYA target level, then you won't get any savings since you'll just be adding an extra product to the water at extra cost.

I suppose if there were a very inexpensive source of lanthanum, then the argument could be different. On this forum, we try and use methods that are more broadly applicable. We do separate some by whether or not one uses an SWG and based on the type of pool surface, but with phosphate removers we'd have to partition into a more complicated cost analysis for some pools with much higher phosphate levels. It also conflicts with the use of the better HEDP-based metal sequestrants. So if there were a much lower cost of lanthanum, then the argument could change. Unfortunately, lanthanum prices have risen as with other rare earths due to the use of such metals in the semiconductor industry and some restrictions of export from China. Cerium might be another alternative whose price may not rise as much (solubility of phosphates with rare-earths from atomic number 57-63 and 68-70 are very low).

If one wants to lower their target FC/CYA level, then there are other methods that do this as well such as using Polyquat 60 weekly or using 50 ppm Borates in the pool except we don't recommend lowering the FC/CYA level for the latter since we haven't figured out how much mild algicidal effect the borates have (we know it does, but haven't quantified it). For Polyquat, I know that one could lower the FC/CYA target by at least half (but probably not to less than one-third the original target) and not get green algae growth. These methods and phosphate removers are all extra cost and that cost varies depending on initial phosphate level (for phosphate removers) and pool size. Note that a lower FC/CYA level has a slower disinfection rate though that's probably not a concern in a residential pool, but it also has a slower oxidation rate so pool water may get duller if circulation/filtration isn't in great shape. At least by using the Polyquat, it's also a clarifier so helps to compensate for this.

In your situation, for you to maintain the same FC/CYA level but to use a phosphate remover is just extra cost. If you knocked out the algae and then maintained the proper FC/CYA ratio, you wouldn't need the phosphate remover. So you should look at it as 1) an alternative that might be lower cost for your initial starving of existing algae IF it works and 2) as insurance for the future at extra cost.

 

[rock]

Re: Orenda PR-10000 versus Lanthanum Chloride for phosphate

your current situation which probably wouldn't have happened had you had your own proper test kit and maintained FC/CYA properly and possibly improved circulation.

Understood.

if there were a much lower cost of lanthanum, then the argument could change

I'm hopeful there is a cheap source of rare earths, perhaps from an industrial supplier.

(solubility of phosphates with rare-earths from atomic number 57-63 and 68-70 are very low).

I'm pretty rusty on my rare-earth chemistry (I don't know that I've ever known it)...

Is this a good list of rare-earth salts that might precipitate phosphates?
- Lanthanum chloride LaCl₃
- Lanthanum carbonate La₂(CO₃)³
- Cerium chloride CeCl₃
- Cerium carbonate Ce₂(CO₃)³
- ?

EDIT: US Patent 3956118, "Removal of phosphate from waste water", to my untrained eye, seems to imply lanthanum/cerium might work as the chloride, sulfate, or nitrate (and maybe even the hydroxide if the pH is right).

 

[chem geek]

Re: Orenda PR-10000 versus cheap Lanthanum Chloride salt cry

The rare earths that precipitate phosphate the best are the following (taken from this paper) where I put asterisks by the best:

Number . Symbol . Element ........... pK_AP
... 39 ......... Y ........ Yttrium ............ 24.76
... 57 ......... La ....... Lanthanum ...... 26.15 ***
... 58 ......... Ce ...... Cerium ............. ? (probably 26.1) ***
... 59 ......... Pr ....... Praseodymium . 26.06 **
... 60 ......... Nd ...... Neodymium ..... 25.95 **
... 61 ......... Pm ...... Promethium ..... ? (probably 25.97) **
... 62 ......... Sm ...... Samarium ........ 25.99 **
... 63 ......... Eu ....... Europium ........ 25.75 *
... 64 ......... Gd ...... Gadolinium ...... 25.39
... 65 ......... Tb ...... Terbium ........... 25.07
... 66 ......... Dy ...... Dysprosium ...... 25.15
... 67 ......... Ho ...... Holmium .......... 25.57 *
... 68 ......... Er ....... Erbium ............. 25.78 *
... 69 ......... Tm ..... Thulium ........... 26.05 **
... 70 ......... Yb ...... Ytterbium ......... 26.17 ***
... 71 ......... Lu ....... Lutetium .......... 25.39

The pK_AP is the negative logarithm of the activity product which is related to the solubility product. A higher number is less soluble. You would usually use the chloride salt of the above for least side effects though the quantity you will be adding is rather small so sulfate is OK as well. The carbonate doesn't dissolve as well and stays cloudier longer. The hydroxide may raise the pH and also cloud up more so I'd stick with either the chloride or the sulfate (the chloride preferred).

However, I think the entire pursuit of getting lower prices from an industrial supplier is folly since you'd have to buy such large quantities to get wholesale or significantly discounted prices. It would only make sense if you were going to resell the product, but for your own pool bulk pricing by the ton isn't going to do you much good. If you are mostly focussed on saving cost and don't care about risk, then use a copper sulfate product to prevent algae growth and operate at a much lower FC/CYA ratio. Just be sure the copper levels and pH don't get too high to prevent plaster staining and blond hair turning greenish.

 

[smackdab]

I know phosphate removers aren't needed but I like to browse around the forum and try to understand more and more advanced chemistry type things. I just recently joined but have been a lurker for awhile. I hate to revive an old thread but I figured this is the best place for my question.

I see the above and can understand somewhat the conclusion that 10,000 ppb of phosphates would require 977 grams of anhydrous lanthanum chloride to remove them. Then I scroll down and see lanthanum carbonate (since supposedly its phosfree) and I wonder if it works out to the same amount or different. Lanthanum carbonates molar mass is 457.838 g/mol so I assume it would be the same equation in post #3 but substitute lanthanum chlorides g/moles (245.26) with lantanum chlorides g/moles (457.838) to get the grams needed. Would this be correct?