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

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^smack, that's true in terms of initial reactiveness, but a long time resident chemist on this board had also described a limiting factor in terms of growth rate of algae (sunlight, reproduction rate etc.)

His conclusion at the time had been that while high PO4 can make water more "reactive" in terms of an initial algae outbreak, that ultimately the growth pace was self-limited once it started, ergo treatment with chlorine (in the TFP manner) would still eradicate it ;)

I've never had algae, despite my 50,000 ppb po4, so I can't prove it, though I have inadvertently tested the theory in my separate fountain by using my own pool water to fill it, then forgetting to maintain chlorine ;) It took about 3 days to go green, but was back to clear within a few hours after a bit of bleach was added.

My own interest in high po4 was as a person reliant on sequestrants due to well and switching to swg, which could, according to the industry, get phosphate scale and wreck the cell.

My cell to date is operating perfectly, producing expected FC for run time, at 5 ppm for a cya of 70 water shows no nascent algae (crystal clear) and my consumption is about 1.5 ppm FC per day.
 
Dave,

It's up to you if you want to shut down this thread or leave it be. I feel it has valuable information in it and I have learned a lot from the discussions in it. I have not added much to it lately because my own experience with phosphate removal is still on-going and I am collecting data on my pool. My intention is to continue with that and present my findings at the end of the season when I have had the time to collect enough data to draw proper conclusions. Yes, this thread has strayed form the original question and Kate has fascinated us all with the on-going saga of her high phosphate pool and SWG performance. But, if that's the issue than one of the Mods could simply go back and split off those posts into a separate thread.

As to your conversations with your daughter-in-law, she has a very interesting job and it would be great to hear from her directly. Why not give her a Guest account and perhaps she can share more of her insights directly? I know I would have lots of questions for her.

I do take issue with something that you relayed in your conversation with her that is not correct on the science and was perhaps an oversight or simply a matter relaying her words. Algae need BOTH nitrogen (N) and phosphorous (P) for life, there is no cross-substitution of the two. While it is true that they are both essential micronutrients and it doesn't take much of them in order for algae to live, if one of those micronutrients are completely missing (either zero nitrogen or zero phosphorous) then life simply can not happen. Now there are some complicated situations where colonies of organisms can reuse some of these micronutrients as members of the colony die and release them into the water but this is not a typical situation and still represents a nutrient-limited environment.

In general, here's my take on your conversation with your daughter-in-law - I don't disagree with what you talked about. Chlorine does kill and it is effective. And no one believes (except maybe pool stores) that you can effectively replace chlorination with phosphate removal. There is no practical way to achieve zero phosphates and there is no way to get rid of algae by simply controlling phosphates. The only people that try to sell that kind of snake-oil logic are pool stores.

The real question isn't can you keep a pool algae free by limiting phosphates. The real question is - can you limit phosphates in your pool to a low level and thereby make it easier to care for? Said another way, if you lower the level of micronutrients in you water, how does that affect the growth rates of algae? What benefits might the pool owner receive in terms of time to react to problems?

Here's an analogy I can think of - why is it that South Korean children grow at normal rates (stature, weight and health) but North Korean children are several inches smaller, weigh less and suffer higher rates of infant mortality than their South Korean counterparts. The answer - starvation and malnourishment. SO if you mass your army on the border (chlorine) and you desire to win the fight quickly, what kind of enemy would you rather face? A well-fed, energetic enemy (high phosphates) or a malnourished and sick one (low phosphates)? Which enemy can you defeat more quickly?

The above analogy is a simplistic one, of course, but it gets to the basic point - if one lowers phosphate levels, is there an impact on pool care? Even if the answer to that question is "yes there is", one still has to work out situations where it is applicable. For one, phosphate removal is pointless in a pool like swampwoman's because it would be a constant losing battle as she adds sequestrant to her water regularly. There may be other situations where the costs associated with phosphate removal do not offset the benefits. But no one would ever know if no one ever tries to answer the question.

Enough said. I will carry on with this thread and my own experiments. People are free to read or to not read what is here. No one is demanding that phosphate removal be a regular part of pool care, if anything, it could just be another tool in the toolbox.

Respectfully,

Matt
 
I look forward to seeing the results of your testing Matt both the good and the bad. Thank you greatly for taking the time to help us all learn more about this topic.
 
JoyfulNoise said:
It's up to you if you want to shut down this thread or leave it be. I feel it has valuable information in it and I have learned a lot from the discussions in it.

Enough said. I will carry on with this thread and my own experiments. People are free to read or to not read what is here. No one is demanding that phosphate removal be a regular part of pool care, if anything, it could just be another tool in the toolbox.
Click to expand...
I didn't gather from Dave's post that he wanted to close the thread, and I'd hope not, that's what the deep end is for!

I've been following along (silently) because it is all very interesting. I currently don't feel any need to test for or remove phosphates, but if it's shown it could lower FC use to the point where I could lower my SWG production, it would be something to think about.
 
Fertile Pond Report ;)

SWG continues flawless FC production and water is crystal clear despite high fertility ;) Notably, swg has also not yet asked to be cleaned. Beginning to believe that, at least in the Aquarite t-15 with the self-cleaning polarity switching, that phosphate scaling is not the issue techs would have one believe these days.

FC 5
Cc 0
Ph 7.8 (adjusted to 7.6)
TA 100
Ch 100
Cya 70
 
You could always pull the cell and look at it anytime you want (no need to wait for your electronic task-master to tell you what to do :) )...just unplug it, turn two union connectors and, viola, easy inspection.
 
Just because you have a wicked high phosphate level and I want to see for myself, I took my own advice:

Cleaned two identical buckets with bleach, filled each with 3 gallons of pool water, neutralized the chlorine with hydrogen peroxide and added 1.5 tspns of 20-20-20 fertilizer to one bucket which is 120 ppm N, 120 ppm P, 120 ppm K. You state you have 50 ppm of PO4. I don't know if that equals 50 ppm of P but 120 ppm surely is enough to see some results and should be higher than what any pool will be. It did turn the water a blue tinge from the tracer dye in the fertilizer.

It has been 4 days and I see no algae in either bucket. They both are still clear, besides the blue tinge.
 

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smackdab said:
Ok thanks. I don't want to hijack the thread here. I just wanted swampwoman to know where her pool stands in regard to no algae happening in my bucket after 4 days. I may start a thread on what happens.
Click to expand...

Keep it here as this would be the best spot for it.

When you added peroxide, did you test and readjust the pH of the water? Did you test to ensure the FC was zero? Peroxide neutralizes free chlorine and creates HCl in the process. Assuming you had enough alkalinity in the water, the pH shouldn't drop too much but it's always best to document any differences in water chemistry.
 
Smackdab, cool test! And this is the place for it...its an exploration/discussion/experiment thread so there's nothing to hijack! ;)

I have a 5 gal bucket so I could easily set one aside too and just see how many days it would take at my particular level. I could let the FC just wear off naturally. I have 50 ppm borates and residual copper of about .2-.3 (prior owner or copper pipes, not sure which) so that may affect results. I have no control sample though...unless I just use a bucket of well water or softened water for comparison, which makes sense. No chlorine in any of my home water so it might actually turn faster.
 
No I didn't readjust the pH. I did think of rechecking it but 1 drop of 31.45% MA is alot for 3 gallons of water. Kinda hard to adjust perfectly. I don't know if I can actually check the pH of the fertilizer bucket since it is somewhat blue. I'd say the fertilizer may have changed the pH of the water in that bucket, but which way, down? Any suggestions?

I tested with FAS-DPD and the OTO test, no chlorine. I calculated 1 drop of 3% hydrogen peroxide per gallon of water removes 1 ppm of FC. Well actually 4 drops per 3 gallons for 1 ppm FC.

I have very little phosphates if any in my pool since I have checked before and used a phosphate remover to remove them. I believe I had 200 ppb the first and only time I checked. I figured it wouldn't matter if there was a little bit in the pool water since the fertilizer bucket would be 120ppm P higher anyways.

Pool Water Test Results at the time was:
FC 8
CC 0
PH 7.5
CYA 40
TA 80
CH 300
TEMP 82 F
Pool water has been adjusted since then.

I still have the phosphate test strips. I have no way to test nitrates. I may just start the test over if I can get everything in order on what I need to do to eliminate all the variables possible to make it right. I'm completely open to suggestions. Still no algae in either bucket for some reason.
 
Ok I guess I should have tested the pH in the fertilizer bucket to start with. It isn't blue enough to affect the test and it's a 6.8 so no telling where the pH went. I'll just dump these buckets out and start again sometime in the next day or two.
 
There's a general problem with these bucket tests for something like algae - you can't create algae from nothing. In other words, you are taking a sanitized and clean bucket and adding to it sanitized water (your pool has no algae in it, right?) and expecting algae to form out of thin air...not going to happen.

The proper way to do these types of biological growth experiments would be to have two buckets, one with fertilizer and one without, and then inoculate them with a known dose of algae and then see what the differences are. You can't just wait for the buckets to randomly pick up an algae spore and go. You have to remember that your pool is a large surface area, open-body of water that gets visits from dust, dirt, critters and bugs all day long. Thus it is constantly bombarded by possible sources of algae and pathogens. A 5 gallon bucket with approximately 1 sq ft of surface water area is not equivalent to your pool.

So, while you're rethinking your chemistry (some fertilizer is designed to be acidic because that releases micronutrients like iron better), you may also want to rethink how you can dose your water with an algae source.


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One option might be to collect random samples of leaves from the yard, adding maybe 20 leaves to each bucket. Maybe add a few tablespoons of surface soil from the garden in a nylon knee high, or something like that. Put it all in for an hour or two, then take them out. I think that would speed things up. You could reduce confounding factors between buckets by pouring the water back and forth a few times between buckets before adding the fertilizer.
 
needsajet said:
One option might be to collect random samples of leaves from the yard, adding maybe 20 leaves to each bucket. Maybe add a few tablespoons of surface soil from the garden in a nylon knee high, or something like that. Put it all in for an hour or two, then take them out. I think that would speed things up. You could reduce confounding factors between buckets by pouring the water back and forth a few times between buckets before adding the fertilizer.
Click to expand...

Or go to a local pet store and swab the insides of the fish tanks...those are always nasty and full of algae :D


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No algae in the pool. I believe I do have some green algae in a bird bath. I'd have to go look. How would you suggest I take it out and divide it up for the two buckets? I know this is isn't going to be a lab type 100% no variable test but I want to make it as good as I can without sending off for some algae spores. There is also a lake up the road that may make a good source of algae spored water that I can dose the buckets with.

I've already started my buckets again. I'm not going to lower the FC with anything but let the FC go down on its own. Also I haven't added any fertilizer to one bucket yet because I want the FC to go down first.

Here's what I've done today:

1) Cleaned two identical buckets (with bleach) and added 3 gallons of pool water to each bucket.
Pool water test results: so this is each bucket at this time.
FC 8
CC 0
PH 7.4
CYA 50
TA 70
CH 300
BORATES 0
SALT 0 (of course there is some salt, but never have added any or tested for it, no SWG)
PO4 0 (Aqua Check test strips. Test sample was clear, first comparison block was a light blue at 200ppb.)
TEMP 86 F
 

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