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

[Pool_Medic]

Interesting how this site has changed its views over the past 13 years. I for one use phosphate removers in all my pools. Yes it’s a bit of an add on to the clients but I think it’s well worth it should chlorine levels ever drop for whatever reasons.

 

[Jimrahbe]

PM,

Do you just use it or do you test to determine what the level is before you use it???

Thanks,

Jim R.

 

[Leebo]

Lee, it should be pointed out that you acted on phosphates based on your own testing with the K-1106.

I was told by my pool guy that I had high phosphates. He said the office told him to bring a water sample to the office to test for every pool he services. I got a K-1106 test kit when I ordered phosphate remover. But before I used it I did the K-1106 in front of my pool guy. Guess what, negligible phosphates. I still have the unopened bottle.

If you are going to treat phosphates base it on your own testing.

Without a doubt! In fact, I’d like to repeat what you just said,

If you are going to treat phosphates base it on your own testing.

Interesting how this site has changed its views over the past 13 years.

There’s clearly times when attempting to keep up with phosphates are gonna cost more than trying to just live with them. There’s also so many times when stores recommend them that the chemical simply won’t work. The amount of horrid advice around this product is amazing. That said, the product isn't as horrid as other products on the market. The knowledge how/when to use the product must be learned first. Lack of chlorine is almost always the root cause of algae, but in my experience the product isn’t always a worthless investment.

 

[JoyfulNoise]

I've thought quite a bit about this over the last few years trying to come up with a chemical explanation for why higher PO4 levels might contribute to problems with SWG's beyond the usual explanation of "it's algae food" and I've not found much. Sure, calcium phosphate scale could coat a plate and cause a loss of FC production but that's not a likely scenario in a lot of pools (you need high CH, phosphates and pH to make it happen). The one theory I'd like to test would require a fully outfitted chemistry lab running multiple chlorine generation experiments using membrane-separated cathodes and anodes to analyses oxidation and reduction products along with high resolutions SEMs .... anyone got a few million dollars and an industrial lab space available???

 

[Pool_Medic]

I treat any pool above 1000 ppb. Part of my service includes crystal clear water or I eat the expense of clearing it up.

 

[Saturn94]

@Leebo, I had a very similar experience this year.

My first SWG cell lasted almost 10 years which I know is probably above average to begin with. However, my second cell that I just replaced at the beginning of this year only lasted 4.5 years. The difference? I believe it has to do with phosphates but let me explain.

For the first 10 years of my pool experience, I would replace the pool water every year or every other year because of high CH levels. Unbeknownst to me, I was also keeping phosphate levels down as our fill water has over 200 ppb of phosphates. The year after I replaced my first SWG cell, our area came under drought water restrictions and we were asked to not replace pool water so I didn't for the next 4 years. What I noticed as time went on is that it became harder and harder to keep algae at bay with FC levels near the lower end of the SWG recommendations (5%) as I had done for years. Right before the cell failure, I had to run closer to 10%. After the cell failure, I tested the pool for phosphates thinking that it might be related and sure enough the level had climbed to over 4500 pbb. So a few months ago, I removed the phosphates and now am able to run again at a 5% CYA FC level.

So while it may be true that you can operate a pool just fine with high phosphate levels, it does come at a cost of higher FC levels and in my case, more frequent SWG replacement. The cost of those 4 years of cell life far outweighs the cost of the treatment. So in the future, I will be keeping an eye on phosphate levels.

Interesting. My experience has been different.

My pool always has high phosphate levels, over 1000 per the Taylor test kit, due to the steady diet of Jack’s Magic Purple Stuff I’ve been using for many, many years. I’ve not noticed any impact on SWCG cell performance or lifespan (last T15 cell lasted 7 years).

Jack’s claims the Purple stuff helps protect salt cells. I also add boric acid, which I understand can help prevent salt cell scaling by limiting the pH rise in the cell.

Perhaps this explains my experience? I really don’t know, but find our different experiences interesting.

 

[duraleigh]

Interesting how this site has changed its views over the past 13 years.

TFP has not "changed it's view" on phosphates. Some folks here believe it is helpful, others do not. I am firmly on the "do not" side of things. I really don't like the complexity of application (it's all over the map) and I especially don't like how you would ever determine it's effectiveness........it seems like you have to GET algae, and then decide that you didn't get as much as you used to????? That philosophy leaves out the thousands of pools that never get it in the first place.

The discussion will go on and on but it will take a LOT more definitive reports of it's effectiveness before TFP "changes it views"

 

[Leebo]

I especially don't like how you would ever determine it's effectiveness........it seems like you have to GET algae, and then decide that you didn't get as much as you used to?????

One could in theory reverse this mindset. One could take a pool that's low in phosphates and algae free and maintain it for a period of time measuring the chlorine usage. As you've mentioned, there are thousands of pools that fall into this category. You then could add phosphates into the water by adding fertilizer and continue to maintain the same "pattern." If removing phosphates are totally worthless then the water should keep it's sparkle and the chlorine usage should remain the same. Now granted this assumes that the user maintains the same CYA level and the pool see's the same amount of swimmers.

 

[Catanzaro]

I think for the most part, phosphate removers are like Poly 60 at closing a pool for the season. It is basically extra insurance across the board. Yes, you can manage without PR and get by, and you can manage without Poly 60 and get by. It is a matter of preference. Simplicity is probably best for almost all pool owners. For me, I treat phosphates once per year, and my levels are at the 500 ppb before the yearly addition of Orenda PR.

 

[mas985]

Interesting. My experience has been different.

My pool always has high phosphate levels, over 1000 per the Taylor test kit, due to the steady diet of Jack’s Magic Purple Stuff I’ve been using for many, many years. I’ve not noticed any impact on SWCG cell performance or lifespan (last T15 cell lasted 7 years).

Jack’s claims the Purple stuff helps protect salt cells. I also add boric acid, which I understand can help prevent salt cell scaling by limiting the pH rise in the cell.

Perhaps this explains my experience? I really don’t know, but find our different experiences interesting.

My comments were not about the SWG production of CL but about the daily consumption of FC as well as FC targets. As far as I can tell, my SWG was producing the same FC levels with and without phosphates. What changed for me was how much FC was used and also the acceptable lower limit of the FC target range. With low phosphates it was 5% of CYA and then over several years it doubled to 10% of CYA with much higher phosphates. Unless you remove the phosphates from your own pool and see how much lower you can adjust the SWG setting, how would know that you would not benefit from lower phosphates? If you could potentially extend the life of your SWG, wouldn't that be of interest? For me it was worth the experiment.

We know that the higher the FC level, the faster it will kill algae. We also know that the higher the phosphate levels the higher the reproduction rate of algae. We also know that algae spores continuously drop into most any pool so even though a pool may have no observable algae and the water looks crystal clear, it is still likely that some algae exists in some part of the pool at some point in time. What is important is that the FC kill rate is always kept higher than the algae reproduction rate so it doesn't take over the pool. I have experienced situations where these two rates were approximately equal and the water had a slightly dull look to it but no visible algae. This is where you can reach a tipping point and any other unexpected excess demand on FC, could push the pool into an algae bloom. The simple solution of course is to raise FC levels and yes this probably works close to 100% of the time. But it does require additional CL.

The FC levels in pool school do a good job of accounting for most pool situations but is important to remember those are not hard limits but represent a point where the probability of an algae bloom is significantly reduced although never entirely eliminated. I am sure there is a probability distribution curve that represents the chances of getting algae at every FC level. However, this distribution will be affected by many factors; pool circulation, heat, UV exposure, organic load and nutrients in the pool. If I can shift this probability distribution lower by removing phosphates and minimizing long term CL use, then it seems like a no brainer to me.

 

[mguzzy]

@Leebo, I had a very similar experience this year.
....So while it may be true that you can operate a pool just fine with high phosphate levels, it does come at a cost of higher FC levels and in my case, more frequent SWG replacement. The cost of those 4 years of cell life far outweighs the cost of the treatment. So in the future, I will be keeping an eye on phosphate levels.

TFP has not "changed it's view" on phosphates. Some folks here believe it is helpful, others do not. I am firmly on the "do not" side of things. I really don't like the complexity of application (it's all over the map) and I especially don't like how you would ever determine it's effectiveness........it seems like you have to GET algae, and then decide that you didn't get as much as you used to????? That philosophy leaves out the thousands of pools that never get it in the first place.

The discussion will go on and on but it will take a LOT more definitive reports of it's effectiveness before TFP "changes it views"

What @mas985 sees parallels my experience, albeit anecdotal. For the first 5 years I owned my pool I struggled with maintaining it, but switching to a SWG made a huge difference. And then I spent the next decade working out how my SWG behaves. I have no logs from the time, and would not know about the TFP protocol for another 15 years. I've come to learn my pool gets lots of organics in the winter. If I don't reduce the phosphates they contribute at the onset of the year I have problems maintaining the pool. Its pretty cause and effect. As to the chemistry involved.. I don't have the time to figure that out.

But here's what I do know. There is more involved in maintaining a small man made lake than just keeping the FC up. Its a major component for sure. I know what kind of external contributions I get to my pool: trees leaves, redwood branches, soot from local fires, dog hair, bird poop, dead rodents... oh and swimmers too, its a cornucopia of a chemical soup. I know from my experience in my previous science career there are all kinds of nutrient chemicals, nitrates, nitrites, phosphates, iron.. yadda yadda. There are likely multiple species of algae, zoo plankton too, bacteria, the occasional water bug, mosquito larvae trying to get a toe hold. Ever look at your pool water in a microscope? To try and boil it down to one sanitizing agent is pretty simplistic. As well as it is simplistic to say all pools behave the same. It may work for some in a more controlled environment... in mine I need to control at least the phosphates. And experience bears that out.

As @JoyfulNoise noise says it would be cool to back up the phosphate claim with some real science. It would be fun to design an experiment where we create a database of the combined test logs of all the TFP users. I bet a good old fashioned ANOVA would find some interesting trends. We are already half way there as everyone uses a standard sampling regiment.

 

[duraleigh]

AS this discussion continues, I am reminded of who our primary audience is......they are folks who likely have green pools and want to go swimming.....period.

TFP is not trying to teach the level of sophistication that you phosphate proponents have. More importantly, is the average "want to go swimming" member even capable or interested in conducting the level of pool care that you maintain? We all know that answer......they are not.

If TFP was a discussion forum about the VERY BEST, most sophisticated ways to manage pool water, I would be all in on exploring phosphates but we are not that forum.

Now, the next thing I get when I bring up this idea of simplicity is that we "owe it to our members" or that we should not "withhold information" and that we should teach all levels of sophistication. I don't buy into that.

When Thomas Edison did that thing with the light bulb, he didn't spend countless hours trying to explain the necessity of having that filament in a vacuum, he showed us where the switch on the wall was and we were happy.

 

[Saturn94]

My comments were not about the SWG production of CL but about the daily consumption of FC as well as FC targets. As far as I can tell, my SWG was producing the same FC levels with and without phosphates. What changed for me was how much FC was used and also the acceptable lower limit of the FC target range. With low phosphates it was 5% of CYA and then over several years it doubled to 10% of CYA with much higher phosphates. Unless you remove the phosphates from your own pool and see how much lower you can adjust the SWG setting, how would know that you would not benefit from lower phosphates? If you could potentially extend the life of your SWG, wouldn't that be of interest? For me it was worth the experiment.

We know that the higher the FC level, the faster it will kill algae. We also know that the higher the phosphate levels the higher the reproduction rate of algae. We also know that algae spores continuously drop into most any pool so even though a pool may have no observable algae and the water looks crystal clear, it is still likely that some algae exists in some part of the pool at some point in time. What is important is that the FC kill rate is always kept higher than the algae reproduction rate so it doesn't take over the pool. I have experienced situations where these two rates were approximately equal and the water had a slightly dull look to it but no visible algae. This is where you can reach a tipping point and any other unexpected excess demand on FC, could push the pool into an algae bloom. The simple solution of course is to raise FC levels and yes this probably works close to 100% of the time. But it does require additional CL.

The FC levels in pool school do a good job of accounting for most pool situations but is important to remember those are not hard limits but represent a point where the probability of an algae bloom is significantly reduced although never entirely eliminated. I am sure there is a probability distribution curve that represents the chances of getting algae at every FC level. However, this distribution will be affected by many factors; pool circulation, heat, UV exposure, organic load and nutrients in the pool. If I can shift this probability distribution lower by removing phosphates and minimizing long term CL use, then it seems like a no brainer to me.

Thanks for the clarification.

I’ve not experienced any noticeable change in where I need to keep FC as phosphate level increased. The first few years when I wasn’t using a sequestrant and actively kept phosphates low, I had to make sure FC didn’t drop below 5ppm (CYA at 80). Since using the sequestrant (ie actively adding phosphates...eek!) and ceasing phosphate control, it’s still ok as long as FC doesn’t drop below 5 (below 5 the liner starts to get slick). That said, since 5 is the absolute minimum for my pool, I target 6-7 for some wiggle room. I don’t like living on the edge...lol.

In any case, without the sequestrant the pool will stain, so stopping the sequestrant is a no go. And since the sequestrant is constantly adding phosphates, it doesn’t make sense for me to actively fight phosphate level.

I can’t explain why the difference, other than not all pools seem to behave the same. I’m sure there are different variables at play here that isn’t obvious.

 

[Saturn94]

AS this discussion continues, I am reminded of who our primary audience is......they are folks who likely have green pools and want to go swimming.....period.

TFP is not trying to teach the level of sophistication that you phosphate proponents have. More importantly, is the average "want to go swimming" member even capable or interested in conducting the level of pool care that you maintain? We all know that answer......they are not.

If TFP was a discussion forum about the VERY BEST, most sophisticated ways to manage pool water, I would be all in on exploring phosphates but we are not that forum.

Now, the next thing I get when I bring up this idea of simplicity is that we "owe it to our members" or that we should not "withhold information" and that we should teach all levels of sophistication. I don't buy into that.

When Thomas Edison did that thing with the light bulb, he didn't spend countless hours trying to explain the necessity of having that filament in a vacuum, he showed us where the switch on the wall was and we were happy.

I realize TFP guidelines are there for the average pool owner, and for that they work very well (my pool thanks you!)! But can’t TFP also appeal to the more “advanced” pool owner? After all, this is in the Deep End section, which I thought was for discussing more advanced pool care ideas?

Perhaps I just misunderstood your post?

 

[Leebo]

This was posted in another thread but I personally feel it would be appropriate to discuss here. Please keep in mind I work in logistics, NOT in chemistry. I may totally be incorrect on what I'm about to say. I have done some research on this and unfortunately haven't found any articles that can backup my theory.......but I'd like to ask many of the people here who are FAR smarter than I to help me out.

It also disregards that algae can feed on nitrates in your pool perhaps just as easily or perhaps even more easily than phosphates.......I don't know.

To me this idea doesn't add up. Looking at phosphates like donuts and nitrates like pizza it does seem like if you remove one food source that algae would simply eat the other.......I know I would. What I'm thinking (and I totally maybe wrong) is that that's not correct. Based on some research to maintain my amazing figure it would seem to me algae would need both donuts AND pizza to survive. My theory is that BOTH nitrates AND phosphates are required for algae to continue to live. Remove one and life cannot continue.

Now granted, it’s totally not practical to remove nitrates, so any discussion on nitrate removers are pointless. It’s also not practical to remove 100% of phosphates in the pool. Phosphate removers also will not kill off any person to person diseases. Because of the above it’s true that chlorine at appropriate levels are required to maintain a pool. I totally agree that new users should first focus on keeping the FC/CYA ratio. What I’m still trying to learn however is if phosphate removers serve ANY purpose? Can removing phosphates help a pool owner at all or do they only add cost? Can a pool owner save any time or money by removing phosphates?

 

[Leebo]

In any case, without the sequestrant the pool will stain, so stopping the sequestrant is a no go. And since the sequestrant is constantly adding phosphates, it doesn’t make sense for me to actively fight phosphate level.

If I may ask @Saturn94, what’s your current phosphate level? It sounds like you’ve got a test on hand and have tested in the past so I’d be interested in your feedback.

 

[mguzzy]

@Leebo there is a concept in biology called the "limiting nutrient" it is the nutrient that is the limiting factor in population growth. Phosphorus and Nitrogen compounds are the most commonly considered the limiting compounds because the the producers in an ecological system (the plants) use so much of it. In actuality there is a relationship between how much each one gets used. Some others have postulated ferrous compounds are the limiting factor.. at least in the ocean. While fresh bodies of water may have a different limiting nutrient. I haven't kept up on the limonolgy and biological oceanography literature in a while but that is the basic concept. While I was on a research project we wanted to calculate the primary productivity of the plankton population in our water samples and we used radioactive phosphates and measured their uptake in a single diurnal cycle. So from that standpoint you could say everything eats phosphates.. and you'll limit the growth of the population. But there is probably a whole diet of stuff you would have to curtail to completely stop the growth all together. (the donuts, the pizza, the chips and dip, the Captain Crunch, etc)
All these food analogies have made me think of the concept of "luxury consumption".. I think I'll have a beer.

 

[duraleigh]

After all, this is in the Deep End section, which I thought was for discussing more advanced pool care ideas?

Discussion is absolutely fine. Converting inconclusive discussions into TFP policy or advice dilutes our mission. We are a teaching forum dedicated to help everyday folks solve their everyday pool problems.

Far too often, we have too much "parroting" on this forum wherein responders suggest something they have read here but do not understand the complexity or the caveats of the subject.

"Why don't you try phosphate remover?" may make a responder feel helpful but for the OP starting a SLAM, it is only inserts confusion and does nothing to help OP clear his pool.

So, certainly, reasonable things can be discussed here just like we are doing. That said, don't think that discussions like these don't work their way out into mainstream advice without regard to the many many qualifiers that need to be considered.

 

[Saturn94]

If I may ask @Saturn94, what’s your current phosphate level? It sounds like you’ve got a test on hand and have tested in the past so I’d be interested in your feedback.

The Taylor test tops out at 1000, so it’s at least that, but I suspect it’s much higher. I haven’t tried a dilution test to see if I can pin down a number.

 

[Saturn94]

...Based on some research to maintain my amazing figure it would seem to me algae would need both donuts AND pizza to survive. ...

I like this diet!!?