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

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Saturn94 said:
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.
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I too in this case wouldn't want to add more CYA either here. The thing is however, you've still got your SWG to provide chlorine while you're away. It would only be some malfunction that would cause an issue, be it power failure or equipment breakdown. In these cases you're likely to face some issues anyways as you are now in a scenario that requires manual labor to help out. As another option you could take to save some cash would be to simply manually add chlorine to your SLAM of 31ppm level and let it go from there. Assuming you drop 3ppm FC per day at the end of a week you'll be looking right around 8-10ppm FC......still well within the 6-11 FC goal you would aim for on a normal basis. This is assuming the malfunction occurs on day one too.


Saturn94 said:
Excellent posts, Joyful. :)
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I couldn't agree more with this comment! Great job Matt helping us ALL learn alot more about this subject!!
 
I most impressed with Swampwoman's pool at 25 PPM Po4. That's 25 times what industry says is a problem. I thought I heard from a well known pool chemical expert that 3.0 PPM was where it began to be a problem and real concern.
 
Leebo said:
I too in this case wouldn't want to add more CYA either here. The thing is however, you've still got your SWG to provide chlorine while you're away. It would only be some malfunction that would cause an issue, be it power failure or equipment breakdown. In these cases you're likely to face some issues anyways as you are now in a scenario that requires manual labor to help out. As another option you could take to save some cash would be to simply manually add chlorine to your SLAM of 31ppm level and let it go from there. Assuming you drop 3ppm FC per day at the end of a week you'll be looking right around 8-10ppm FC......still well within the 6-11 FC goal you would aim for on a normal basis. This is assuming the malfunction occurs on day one too.




I couldn't agree more with this comment! Great job Matt helping us ALL learn alot more about this subject!!
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Bringing the pool to SLAM level before leaving it unattended for a week sounds like a good option based on the numbers you presented (I like numbers ;) ). In my earlier post I asked the question if FC would stay high enough all week; it looks like it should unless for some reason daily losses are greater. I may try this next time I go away for a week.

Regarding having other issues to deal with in the event of equipment failure, if I'm at home I can take immediate action to mitigate big problems. I actually had that happen; my pump motor failed and it took almost 2 weeks to get a new one. Fortunately I was home and immediately started manually dosing the pool with bleach (I kept FC a bit above target for good measure). Despite the downtime and lack of circulation, I was able to keep the water clear (bit of dirt on the bottom though). Had I been out of town and not taken precautionary measures, I probably would have returned to a swamp.
 
Raising the pool up to shock level will not be that effective at low CYA especially with warm water. The chlorine loss is proportional to the concentration of hypochlorite (OCl-) and the FC/CYA ratio at shock levels is 40%. Therefore the chlorine loss rate will be very rapid at the beginning of the vacation and tail off towards the end. The only way these high dose FC scenarios work is when you also raise the CYA up to 100ppm or higher so that a larger proportion of the chlorine is protected from UV photolysis.


Sent from my iPhone using Tapatalk,16k gal SWG pool (All Pentair), QuadDE100 Filter, Taylor K-2006
 
JoyfulNoise said:
Raising the pool up to shock level will not be that effective at low CYA especially with warm water. The chlorine loss is proportional to the concentration of hypochlorite (OCl-) and the FC/CYA ratio at shock levels is 40%. Therefore the chlorine loss rate will be very rapid at the beginning of the vacation and tail off towards the end. The only way these high dose FC scenarios work is when you also raise the CYA up to 100ppm or higher so that a larger proportion of the chlorine is protected from UV photolysis.


Sent from my iPhone using Tapatalk,16k gal SWG pool (All Pentair), QuadDE100 Filter, Taylor K-2006
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So much for that option.
 
MarianParoo said:
Yessir, 35-40. Good memory! I know that I "waste chlorine" for the forst several days this way, but I prefer not to use pucks if I am only going on a short vacation.

Would a SWG would tolerate the same prescription?
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I don't see why not.

If I raised FC to shock level and left the SWCG running, it would probably stay around shock level all week if nothing happened.

Would it be bad to have a pool at shock level that long? I'm thinking not since a SLAM could last that long without problems?
 
But again, if you're that low pucks are always an option that can help for very little money. Phosphate removers simply do not make sense in this case.


So let me ask members this question.......how do phosphates enter the pool water??
 

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The major sources of phosphates are actually caused by the pool owner - phosphonate sequestrant use and municipal water supplies that use orthophosphate corrosion inhibitors.

Some people blame wind and sediment but it would take a ridiculous amount of fertilizer rich soil to blow into your pool to have that kind of effect. The breakdown of organic matter can add phosphates but it is also minimal. Even fertilizing a lawn that is close to the pool can't possibly add levels that are considered significant.


Sent from my iPhone using Tapatalk,16k gal SWG pool (All Pentair), QuadDE100 Filter, Taylor K-2006
 
JoyfulNoise said:
The major sources of phosphates are actually caused by the pool owner - phosphonate sequestrant use and municipal water supplies that use orthophosphate corrosion inhibitors.

Some people blame wind and sediment but it would take a ridiculous amount of fertilizer rich soil to blow into your pool to have that kind of effect. The breakdown of organic matter can add phosphates but it is also minimal. Even fertilizing a lawn that is close to the pool can't possibly add levels that are considered significant.
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So unless the user uses a sequestrant or its added to the fill water, is it a safe guess that the user theoretically should have low phosphate levels?? How common is it for cities to add these products to the water??
 
Marcion,

In this thread you made the comment that your phosphate level was around 750ppb,
Marcion333 said:
Patrick, my initial phosphate reading in November 2015, when building the pool was finished, was around 750 ppb.
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Did you ever see any water clarity issues when maintaining the FC/CYA ratio??? This level is far lower than the level of 25,000ppb reported by Swampwoman above.....yet she has reported having low FC loss (around 2-3ppm loss per day at a CYA level of 40) and no water clarity issues. What sort of FC and CYA levels do you maintain your pool at?? What is your daily FC loss on average??

I would expect to see an increase in your FC loss seeing your pool in the Texas climate is different from Michigan's.......but I'm interested in hearing what you've experienced.
 
Leebo said:
So unless the user uses a sequestrant or its added to the fill water, is it a safe guess that the user theoretically should have low phosphate levels?? How common is it for cities to add these products to the water??
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I doubt that cities add anything to water that contributes phosphates to the water supply. But, I believe the most significant contributor of phosphates to water is fertilizer run off into source watersheds for streams, rivers and lakes, from lawn fertilizer and farms. Surprisingly, more so from lawns than from farms. From my koi pond days there were many people unknowingly putting lots of phosphates into their koi ponds when fertilizing their lawns.

Here is one page of many on effects of fertilizer on water resources, Lawn to Lake - The Phosphorus Problem
 
Leebo said:
Marcion,

In this thread you made the comment that your phosphate level was around 750ppb,


Did you ever see any water clarity issues when maintaining the FC/CYA ratio??? This level is far lower than the level of 25,000ppb reported by Swampwoman above.....yet she has reported having low FC loss (around 2-3ppm loss per day at a CYA level of 40) and no water clarity issues. What sort of FC and CYA levels do you maintain your pool at?? What is your daily FC loss on average??

I would expect to see an increase in your FC loss seeing your pool in the Texas climate is different from Michigan's.......but I'm interested in hearing what you've experienced.
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I've never had issue with water clarity. I lowered phosphates because I wanted to ensure I didn't an algae clarity issue.
My FC/CYA ratio has been down to 5% during the winter, but not constantly.
I've kept CYA at 30 over the winter. My chlorine losses have been approximately 1-1.5ppm/day. however, I haven't been getting much sunlight until 11:30am due to shade from the house.
Last week my CYA level was 25 so I put in enough CYA to raise the level to 45 so now my ratio numbers will change.

According to the expert my higher CYA level should allow chlorine level to drop more slowly, but of course summer is coming up with hotter days and longer and more direct UV days so I'm sure my chlorine drop will change from what I mentioned above.
 
Phosphate corrosion inhibitors are widely used in municipal water supplies of older cities and areas where there are a lot cast iron pipes. These supplies can be as high as 400ppb or even more. This is exactly the issue that happened in Flint Michigan where phosphate corrosion inhibitors were not properly deployed as Flint (and many other old Rust Belt cities) still have lead water pipes.

Unfortunately the only way to know for sure is to contact your local water supplier to see how much they add. I haven't done so but, when I get home, I'll test my tap water to see if phosphates are present. My pool water is a couple of years old and the last time I measured my PO4 level it was barely 1000ppb so that's pretty low for several years worth of build up. It would suggest to me that my water supply has minimal PO4.


Sent from my iPhone using Tapatalk,16k gal SWG pool (All Pentair), QuadDE100 Filter, Taylor K-2006
 
pooldv said:
Very interesting! Thanks Matt.

Our Jan 2016 water report shows 65 ppb raw and 15 ppb treated.
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I would expect gray water and reclaimed water supplies to be higher but the treated (potable) water to be lower. Few homeowners deploy gray water on their properties as the post-construction installation costs for gray water systems are prohibitive (I looked into it last year).

At those levels you report, it would definitely be years before you'd ever see any appreciable amount of PO4 in your water from fill and accumulation. So if your current pool water has an elevated level of phosphates and you wanted to try out phosphate removal, you'd likely only need a single dose to drop it to 0ppb and then forget about it for the rest of the year...unless, of course, you plan to dump a few bags if fertilizer into your pool ;)


Sent from my iPhone using Tapatalk,16k gal SWG pool (All Pentair), QuadDE100 Filter, Taylor K-2006
 
Marcion333 said:
I've never had issue with water clarity. I lowered phosphates because I wanted to ensure I didn't an algae clarity issue.
My FC/CYA ratio has been down to 5% during the winter, but not constantly.
I've kept CYA at 30 over the winter. My chlorine losses have been approximately 1-1.5ppm/day. however, I haven't been getting much sunlight until 11:30am due to shade from the house.
Last week my CYA level was 25 so I put in enough CYA to raise the level to 45 so now my ratio numbers will change.
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Thank you for sharing your numbers. I too expect increasing your CYA will reduce your chlorine loss as 25ppm CYA is below what TFP suggests you maintain......but I too expect you'll see a change as the weather warms up and the sun starts shining more. I look forward to hearing your long term results.


Phosphate corrosion inhibitors are widely used in municipal water supplies of older cities and areas where there are a lot cast iron pipes. These supplies can be as high as 400ppb or even more. This is exactly the issue that happened in Flint Michigan where phosphate corrosion inhibitors were not properly deployed as Flint (and many other old Rust Belt cities) still have lead water pipes.
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I too thank you greatly for your comments in this thread Matt! It's cleared up multiple questions I've had.
 

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