Phosphates.....are they worth removing??

[Leebo]

Over the last few day's there has been a few threads started about phosphates and their benefits in pools. Over the years I've formed a few questions concerning phosphate removers and would like to hear other members thoughts about their use.

My first question is a simple one........When are phosphate removers GREATLY beneficial to the average private pool owner??

 

[kimkats]

First off let me ask this??? Can the pool store test for this? How close are they with this test? If not the pool store then how to test?

Kim (who has never thought about this before so guess it is not big deal for me)

 

[Leebo]

First off let me ask this??? Can the pool store test for this? How close are they with this test? If not the pool store then how to test?

Kim (who has never thought about this before so guess it is not big deal for me)

A pool store can test for this, however how close they get always depends on the store. The average homeowner can test using the K-1106 Kit from Taylor.

 

[Saturn94]

First off let me ask this??? Can the pool store test for this? How close are they with this test? If not the pool store then how to test?

Kim (who has never thought about this before so guess it is not big deal for me)

The company that installed our pool also has a retail shop where they do water testing for customers using Taylor test kits. Generally their results were usually close to mine (I use Taylor test kits as well). If I had to rely on pool store test results, I'd go to them first. Other stores I've checked out were terrible. (Btw, I should note I haven't had a store test my water in many years.)

Anyway, the "good" store did have the ability to test for phosphates, though I cannot confirm the accuracy of the results. In my early days of pool ownership when I was relying on them they did check my pool's phosphate level and found it to be high (I don't remember the number....I may have it in my records). I was having issues with the liner getting slick (start of algae outbreak?) despite "proper" FC levels (according to them....I learned different when I found the forums!), which is what prompted them to check phosphate level.

So yes, they can test for phosphates. Also, I understand there's a Taylor kit available and one from Aquacheck. I've thought about trying one out of curiosity.

 

[Saturn94]

Over the last few day's there has been a few threads started about phosphates and their benefits in pools. Over the years I've formed a few questions concerning phosphate removers and would like to hear other members thoughts about their use.

My first question is a simple one........When are phosphate removers GREATLY beneficial to the average private pool owner??

There seems to be differing opinions on this. I've heard from respected "experts" on both sides of the debate.

I'm far from being an expert, though I'm not new to pool care either, so far I've come away with this; for the average owner who carefully maintains proper FC levels, it's likely not an issue. However, keeping phosphates low can act as "insurance" in case FC dips too low, much like polyquat might be used as "insurance" for those who may not monitor FC/CYA balance closely, don't have someone to care for their pool while on vacation/business trips, or perhaps just want some extra peace of mind.

One of the Mods in another thread said it might be important in some specific situations. I'm curious to know what these situations might be.

 

[Leebo]

I'm far from being an expert, though I'm not new to pool care either, so far I've come away with this; for the average owner who carefully maintains proper FC levels, it's likely not an issue. However, keeping phosphates low can act as "insurance" in case FC dips too low, much like polyquat might be used as "insurance" for those who may not monitor FC/CYA balance closely, don't have someone to care for their pool while on vacation/business trips, or perhaps just want some extra peace of mind.

Yes, but wouldn't simply keeping the chlorine level on the upper end of the FC/CYA scale do about the same thing in the majority of these cases? I would think it would cost a good bit less too as these products aren't very cheap to purchase.

 

[PAGirl]

Not sure if this is the proper place for this question.... But, what types of chemicals do the phosphate removers add to the water? Everything we add has some type of residual effect. (Hence why I don't like to add unnecessary stuff.)

 

[Leebo]

Not sure if this is the proper place for this question.... But, what types of chemicals do the phosphate removers add to the water? Everything we add has some type of residual effect. (Hence why I don't like to add unnecessary stuff.)

That's a very good question.....and one I don't know the answer to. Hopefully somebody will chime in to help answer that one.

 

[Saturn94]

Yes, but wouldn't simply keeping the chlorine level on the upper end of the FC/CYA scale do about the same thing in the majority of these cases? I would think it would cost a good bit less too as these products aren't very cheap to purchase.

Good question.

Scenario: I go on vacation for a week...no one to care for my pool while I'm gone. Right after I leave my SWCG dies (eek!). Or for those who manually chlorinate, just no one to add chlorine. Oh, and no tabs for me, those things are evil! Ok, not completely evil, but I'm at max recommended CYA and don't want to add anymore.

So which would provide the best insurance against having a swamp when I return.

1. Just before I leave boost FC to upper end of recommended scale. Would there be enough FC to keep it above minimum until I return?

2. Add polyquat. In my experience this works pretty well. Will it last all week though?

3. Keep phosphates very low. After all, no algae food, no algae bloom, right? Or not?

4. All 3. Gimme all the protection I can get so I won't worry while on vacation! Yes, I'm willing to bet there are members who prefer this option.

I don't know which is best. I would love to hear what others think.

- - - Updated - - -

Not sure if this is the proper place for this question.... But, what types of chemicals do the phosphate removers add to the water? Everything we add has some type of residual effect. (Hence why I don't like to add unnecessary stuff.)

That's a very good question.....and one I don't know the answer to. Hopefully somebody will chime in to help answer that one.

Sorry, I don't know the specific chemistry, but I thought I read that the phosphate remover combines with phosphates to form a substance that settles out of the water. So once you vacuum/filter it out it doesnt leave any chemical behind.

Someone who knows the chemistry please correct me if I'm wrong.

 

[Divin Dave]

I personally do not think phosphate removers are of any great benefit to the average private pool owner who maintains their pool using TFP recommendations.

However there are some rare cases which I believe phosphate removers may be greatly beneficial.

For example:
I've seen several occasions where someone posted on TFP that they or a child seemed to be sensitive or allergic to chlorine and were looking for alternatives. The majority of replies by TFP members were that it was likely something other than chlorine / HOCL causing the sensitivity.... etc...

Whether the science backs up the OP claim or not usually seems to be irrelevant to the OPs on the subject. I'm of the opinion that once a person is convinced that chlorine (or any other chemical), is bad for them, there isn't any changing their minds about it and they only came here in search of validation. But that's another subject. Anyways....

So, I can see that in a rare case where the pool owner keeps the FC low or non-existent for sensitivity or medical reasons, that phosphate remover may in this case greatly decrease the chances of an algae outbreak.

But thats about it.

 

[wjr75]

Proper CYA/FC levels are the answer but people tend to get Lazy :sad:. My question, not that I will use it but what is the cheaper insurance policy phosphate control or polyquat60? I think the chlorine eats the poly so probably the phosphate stuff?

 

[JoyfulNoise]

Lee,

Great thread. Here are my thoughts and responses.

There are two general classes of situation where phosphate removers (PR's from this point forward) could potentially be beneficial -

Recurrent Algae Blooms

There are reports of pool owners who, try as they might, continually fight with algae. They perform a SLAM correctly, pass all three exit criteria and still get algae coming to visit throughout the season. For most of us on TFP, we have to maybe SLAM our pools once and then have gone years without ever seeing algae (I believe chiefwej is the winner of the SLAM longevity contest at 10 years without algae). But there are people for whom the battle with algae is a constant one. In some of these cases, you have to look at extenuating circumstances. It's also helpful to remember that the FC/CYA ratio is NOT a rigorously derived value that is absolute in nature, it's more akin to a statistical value based on a wide sampling of pools. While the 7.5% rule seems to work for most pools, not all pools are covered by it. In those cases where 7.5% does not work to keep algae under control, TFP often recommends going to a higher ratio to keep algae under control (for example, 10%). The problem is, a higher ratio necessarily means a greater chlorine loss rate and more chlorine consumption. In pools with water that is very reactive to algae, determining what role phosphates play can be beneficial. If those types of pools also happen to have high phosphate levels, lowering phosphates, and seeing what impact that has on these "reactive" pools, is a quick and easy experiment to do. If it turns out that lowering the phosphate levels to below 100ppb helps, then that is a net benefit to the pool owner because not only do they get a cleaner pool but also a pool that uses less chlorine. In effect, they save money.

Metal Sequestrants

For some pool owners, living with metals in their pool and fill water is a dreadful experience (just ask swampwoman). Some people have to use metal sequestrants continually throughout the season to keep metals in control and the most common type of sequestrant are ones based on phosphonates (HEDP is one example but there are other phosphonates as well). Phosphonates do a good job of sequestering metals but they are susceptible to chlorine oxidation and will eventually breakdown into phosphates. People who fill from well water that is laced with metals (iron being the most common) also try not to fill their pools too much and so keep them covered and minimize water loss. This has the unwanted effect of building up phosphates over time due to the breakdown of sequestrants as phosphates are like calcium and salt, they only leave the water through fresh water exchange. In this case, PR's would be beneficial at helping to reduce phosphate levels for both algae nutrient control and calcium phosphate scaling (although calcium phosphate scaling only occurs at extremely high levels of phosphates).

As for the chemistry, PR's are nothing more than acidic solutions of lanthanum chloride. When you add the LaCl3 to pool water, it almost immediately reacts with the excess carbonate to form the precipitate lanthanum carbonate (that's where the cloudiness comes from). The lanthanum carbonate then reacts more slowly over time with phosphates to form lanthanum phosphate which is also a precipitate. These precipitates get trapped through filtration and removed via a backwash. So, for the most part, all of the lanthanum is removed eventually by backwashing. If you have a sand filter, then you will very likely need to use a clarifier as well because sand filters are not able to remove fine particulates well (although one could try adding DE first to see if that works). If you own a DE filter, you generally don't need to clarifier as it will only make a mess of your DE filter. Cartridge filters may have more of an issue since they're not as fine as a DE filter but you can't easily use clarifiers or backwash them either. I would say with a cartridge filter, you might need the clarifier but it would be good to strip and clean the filter immediately so that it doesn't get gummed up by the clarifier.

As for costs, most good commercial grade PR's run about $100/gal. An initial dose in most pools might be somewhere between 6-12oz. Depending on the source of phosphates, most people would find that a gallon could easily last a few seasons. Only in those situations where the source of phosphates into the pool water is continuos (sequestrant use or municipal water that uses high levels of orthophosphate) would you see a much higher rate of PR use. So I think for the casual user of PR's, the cost is not very high.

Best wishes,
Matt

 

[Swampwoman]

+1 on Matt's description of my case.

Just a few tidbits to add.

1. The Taylor phosphate kit doesn't actually test high enough for my phosphate level, which is roughly 25000 ppb (note phos is read as ppb not ppm)...I use an aquarium kit that goes higher and still have to dilute.

2. Despite this comparatively crazy high phosphate level, I've never had algae because I always maintain FC:cya...so your question, Lee, about whether phosphates affect most pool owners has GOT to be pretty much NO if they maintain FC (Mind you, I ride a point higher than the chart suggests to ensure I never drop below.)

3. However, this level would certainly void a swg warranty, and in truth, is high enough to possibly foul the plate and cause an swg to not perform (it actually also depends on calcium level for the formula to know when it would scale in the high ph environment of the plate itself, I am given to understand.)

4. There is quite a bit of literature/conversation in the pool tech world about reducing high phosphate levels as a response to mysterious swg failure where apparently, same is reported to work.

5. For these reasons, phosphate level "might" become germane for people with SWGs who aren't producing enough chlorine and who are getting frequent algae outbreaks

6. We should be conscious that swg folks not be told to use hedp products that we typically recommend and instead recc either jacks purple, which does have phosphate but alleges to clean cell, or jacks magenta, which doesn't contain phosphates but which also is contraindicated for polyquat 60 and clarifiers.

7. Lastly, you don't have to be on well and using hedp to get high phosphate levels....many municipalities treat water sources with hedp-type products. So if one can't figure out where the phosphates are coming from, they can test their source water

Ps - I had actually checked Orenda online and its selling for $139/gallon...I had checked because I was going to do my two-gallon treatment on opening in order to switch to SWG on opening until hubby convinced me we should wait until we after we replaced the liner and trucked in fresh water since our only real reason for swg switch was so that I didn't have to lug chlorine "when old." Apparently, not old and infirm enough

 

[Patrick_B]

So, you control Algae with 25000 PPB of Po4 with a mere Chlorine increase? Out of mere curiosity, how high above the charts do you bump the FC?

 

[Leebo]

Scenario: I go on vacation for a week...no one to care for my pool while I'm gone. Right after I leave my SWCG dies (eek!). Or for those who manually chlorinate, just no one to add chlorine. Oh, and no tabs for me, those things are evil! Ok, not completely evil, but I'm at max recommended CYA and don't want to add anymore.

So which would provide the best insurance against having a swamp when I return.

1. Just before I leave boost FC to upper end of recommended scale. Would there be enough FC to keep it above minimum until I return?

2. Add polyquat. In my experience this works pretty well. Will it last all week though?

3. Keep phosphates very low. After all, no algae food, no algae bloom, right? Or not?

4. All 3. Gimme all the protection I can get so I won't worry while on vacation! Yes, I'm willing to bet there are members who prefer this option.

I don't know which is best. I would love to hear what others think.

That to me sounds like a good bit of "if's" that only add confusion to me. I do see your point where a user may wish to use this as an "insurance" during a vacation, but aren't there MUCH cheaper policies out there? Lets take those pucks you've mentioned. Let's assume the user has a 10k gallon pool (simple for math) and manually chlorinates their pool. They currently have a 50ppm CYA level which is at the top end of what TFP currently suggests. The user goes away for a week and uses one puck every other day....so let's say 4 three inch tabs. These tabs would add 20ppm Chlorine to the water while adding 10ppm CYA. It would now only bring the user to a 60ppm CYA level.......still VERY manageable for the average user. Worse case scenario here the user would want to maybe back flush for a few extra minutes to help reduce their CYA levels. This would only cost the user a few bucks versus the rather large amount of money spent on the insurance policy you suggested.

Recurrent Algae Blooms

There are reports of pool owners who, try as they might, continually fight with algae. They perform a SLAM correctly, pass all three exit criteria and still get algae coming to visit throughout the season. For most of us on TFP, we have to maybe SLAM our pools once and then have gone years without ever seeing algae (I believe chiefwej is the winner of the SLAM longevity contest at 10 years without algae). But there are people for whom the battle with algae is a constant one. In some of these cases, you have to look at extenuating circumstances. It's also helpful to remember that the FC/CYA ratio is NOT a rigorously derived value that is absolute in nature, it's more akin to a statistical value based on a wide sampling of pools. While the 7.5% rule seems to work for most pools, not all pools are covered by it. In those cases where 7.5% does not work to keep algae under control, TFP often recommends going to a higher ratio to keep algae under control (for example, 10%). The problem is, a higher ratio necessarily means a greater chlorine loss rate and more chlorine consumption. In pools with water that is very reactive to algae, determining what role phosphates play can be beneficial. If those types of pools also happen to have high phosphate levels, lowering phosphates, and seeing what impact that has on these "reactive" pools, is a quick and easy experiment to do. If it turns out that lowering the phosphate levels to below 100ppb helps, then that is a net benefit to the pool owner because not only do they get a cleaner pool but also a pool that uses less chlorine. In effect, they save money.

So I'm slightly confused here as Swampwoman in the very next post reported her phosphate level as being VERY high yet she still has never had any issues getting algae? What is she doing differently that other users aren't? Is she using more chlorine than others to achieve the same end result??

Metal Sequestrants

For some pool owners, living with metals in their pool and fill water is a dreadful experience (just ask swampwoman). Some people have to use metal sequestrants continually throughout the season to keep metals in control and the most common type of sequestrant are ones based on phosphonates (HEDP is one example but there are other phosphonates as well). Phosphonates do a good job of sequestering metals but they are susceptible to chlorine oxidation and will eventually breakdown into phosphates. People who fill from well water that is laced with metals (iron being the most common) also try not to fill their pools too much and so keep them covered and minimize water loss. This has the unwanted effect of building up phosphates over time due to the breakdown of sequestrants as phosphates are like calcium and salt, they only leave the water through fresh water exchange. In this case, PR's would be beneficial at helping to reduce phosphate levels for both algae nutrient control and calcium phosphate scaling (although calcium phosphate scaling only occurs at extremely high levels of phosphates).

The pool I maintain is filled from a well so I fully understand the experience and the pain these users suffer maintaining their pools. One of the best things we've done several years ago is switched to trucking in fresh metal free water as opposed to filling from a well. That said, in the case that a user continues to use a sequestrant that increases their phosphate levels, at what point would a user ultimately expect to see an issue??

1. The Taylor phosphate kit doesn't actually test high enough for my phosphate level, which is roughly 25000 ppb (note phos is read as ppb not ppm)...I use an aquarium kit that goes higher and still have to dilute.

2. Despite this comparatively crazy high phosphate level, I've never had algae because I always maintain FC:cya...so your question, Lee, about whether phosphates affect most pool owners has GOT to be pretty much NO if they maintain FC (Mind you, I ride a point higher than the chart suggests to ensure I never drop below.)

I thank you greatly for your real world experience and solid numbers. If I may ask.......what CYA and FC levels do you commonly aim for? Do you commonly use a HEDP product??

 

[JoyfulNoise]

So I'm slightly confused here as Swampwoman in the very next post reported her phosphate level as being VERY high yet she still has never had any issues getting algae? What is she doing differently that other users aren't? Is she using more chlorine than others to achieve the same end result??

In my mind, it's not a matter of doing something specific differently but rather a broad spectrum of actions or environmental conditions that let her get away with phosphates that high. Perhaps its the colder water temperatures of her pool or a variability of sunlight that allows it. Maybe closing and opening the pool every season lets her SLAM the pool and start out on a good footing. Perhaps her environment has algae that is not very good at finding a home in pools (remember that the term algae is very general refers to an extremely large class of aquatic organisms).

My point was more along the lines of IF you have recurring algae and IF your phosphates are above normal levels, then it may be worth a try to see if PR's help.

One other point I would like to stress which hopefully does not derail us too much but it is often argued that PR's are worthless because they represent a huge added cost to pools. This objection is not born out by the facts. PR's are actually not really that expensive (except in the case of retail pool stores which sell very weak mixtures at inflated prices). The amount of PR needed to dose a pool and treat it for an entire season isn't much more than a pint in most normal situations. Phosphates build up very slowly over time so, even in a pool that uses sequestrants, you'd likely only need to start the season with a single dose and then maybe add one or two maintenance doses for the entire year. A gallon (128oz) of PR is a HUGE amount and most people wouldn't need much more than a quart. So you can figure, worst case scenario, that a bottle of PR would cost you about $30 or so and could easily last you a full swim season or two. Most people spend about $30 per month on chlorine costs, so a bottle of high quality PR (Orenda PR-10000 or Halosource SeaKlear) does not represent a huge cost.

 

[Leebo]

So you can figure, worst case scenario, that a bottle of PR would cost you about $30 or so and could easily last you a full swim season or two.

It's also $30 that I don't necessarily need to spend correct? If I never have any of the issues you mentioned above there's no need for me to be concerned as you mentioned.....it's only IF you have any issues. Even then, wouldn't increasing the chlorine levels slightly still be a cheaper route rather than spend $30 on the PR and $40 on the test itself?

 

[Swampwoman]

Hi guys. On a break from work so I'll be quick but wanted to answer your questions.

1. I dose to 7 ppm FC at a rounded up CYA of 35/40...I generally "consume" 2-3 ppm a day, depending on debris load. Thus, I treat my minimum of FC to be about 4. Many days its still at 5 when I dose, but as I said, I prefer to ride high if it means avoiding a Slam.

2. I heat my pool all day/night from may to oct to 88 degrees BUT my pool is partly shaded..eg at least 50% (see debris note

3. I never shock/slam on opening...so far...I usually have a residual FC of about 4 ppm and 35-ish CYA and to date, no algae

4. However, I raise FC on closing to almost shock levels after dosing with pucks for a month to raise the cya for winter
...I haven't used polyquat the last 2 seasons...we'll soon see if I regret this due to warmer winter ( I avoid shocking/slamming due to iron, which although mitigated with my switch to soft water, still rides around .5 ppm)

5. One possible difference is that I do filter 24/7...not because I "need" to but because the heating is cheaper if constant and the pump needs to be on if heating...and also because my pool skim catches most of the abundant leaf/key/flower debris I get year round if the filter is on. This reduces load that actually sinks

6. Since I now fill with soft water and ave a vinyl liner, my calcium is super low...which is likely why I don't have phosphate scaling. I suspect if I had a gunnite pool, I might.

Hope that helps give you an idea of just how effective maintaining FC religiously really is despite phosphates

PS I have a sand filter, which is partly why I've avoided the Orenda treatment until/unless I see an immediate need. I also do not drain for winter due to water table (my pool was built in a storm water basin) and existence of drain surrounding pool which handles snow runoff from cover in spring.

 

[JoyfulNoise]

It's also $30 that I don't necessarily need to spend correct? If I never have any of the issues you mentioned above there's no need for me to be concerned as you mentioned.....it's only IF you have any issues. Even then, wouldn't increasing the chlorine levels slightly still be a cheaper route rather than spend $30 on the PR and $40 on the test itself?

Perhaps.

Let's assume you spend $30 per month in chlorine and, because of recurrent algae, you need to use a 10% FC/CYA ratio instead of the usual 7.5%. That's a 33-1/2% increase in chlorine or about an extra $10 per month. 3 months and you've paid for a bottle of Halosource SeaKlear.

In my book, it's worth a try as there no downside to using a PR aside from maybe a few days of cloudy water. I am assuming though that a person has exhausted other options such as a SLAM with an extended hold at high FC (like a black algae clearing process).


Sent from my iPhone using Tapatalk,16k gal SWG pool (All Pentair), QuadDE100 Filter, Taylor K-2006

 

[Saturn94]

That to me sounds like a good bit of "if's" that only add confusion to me. I do see your point where a user may wish to use this as an "insurance" during a vacation, but aren't there MUCH cheaper policies out there? Lets take those pucks you've mentioned. Let's assume the user has a 10k gallon pool (simple for math) and manually chlorinates their pool. They currently have a 50ppm CYA level which is at the top end of what TFP currently suggests. The user goes away for a week and uses one puck every other day....so let's say 4 three inch tabs. These tabs would add 20ppm Chlorine to the water while adding 10ppm CYA. It would now only bring the user to a 60ppm CYA level.......still VERY manageable for the average user. Worse case scenario here the user would want to maybe back flush for a few extra minutes to help reduce their CYA levels. This would only cost the user a few bucks versus the rather large amount of money spent on the insurance policy you suggested.

Btw, I didn't suggest a particular insurance policy as you seemed to indicate. I brought up some options and wondered which might be best for someone who wants such insurance. Personally I don't know which is best.



So I'm slightly confused here as Swampwoman in the very next post reported her phosphate level as being VERY high yet she still has never had any issues getting algae? What is she doing differently that other users aren't? Is she using more chlorine than others to achieve the same end result??



The pool I maintain is filled from a well so I fully understand the experience and the pain these users suffer maintaining their pools. One of the best things we've done several years ago is switched to trucking in fresh metal free water as opposed to filling from a well. That said, in the case that a user continues to use a sequestrant that increases their phosphate levels, at what point would a user ultimately expect to see an issue??



I thank you greatly for your real world experience and solid numbers. If I may ask.......what CYA and FC levels do you commonly aim for? Do you commonly use a HEDP product??

I don't think what I described is such an unusual situation.

I see your point with the pucks, but for a SWCG user who keeps CYA at 80ppm, I personally wouldn't want to add any more. Yes, I could do a partial drain and refill to lower CYA, but then I'd also have to add salt and borates (and maybe have to adjust TA) to bring those levels back up....and of course there's a cost associated with that.

- - - Updated - - -

Excellent posts, Joyful.