Phosphates - to treat or not?

cbj_atx

New member
Mar 31, 2021
4
Austin, TX
Hi there, I'm new here (this is my first post).

Bought a house last summer with a pool and I was lucky enough to have the fall/winter/spring to lurk around here as well as have a little trial and error of my own. At this point, I'm moderately confident in my pool care system and routine. However, as warmer temps start to arrive I know my routine will ramp up a bit.

Here's my most recent water chemistry:

FC: 1.04
TC: 1.24
pH: 8.00
Al: 115
CH: 337
CYA: 98
TDS: 1100
Phos: 1038

I will be following the pool math calculator to super chlorinate and bring down pH and I'm also stopping use of all stabilizer products to try and bring CYA down without draining during our rainy Spring. My question is around phosphates. I have a TON of live oak trees around the pool which are going through their annual Spring dump... first dropping all their leaves and now dropping a boat load of pollen. I assume they are to blame for my high phosphates. Is there a consensus on whether or not I should be treating for them? Leslie's sold me on a phosphate remover from Trade Grade which seems like pretty strong stuff. Is it worse to add these harsh products vs. to have high phosphates?

TIA for any guidance!
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Welcome to TFP! :wave: First thing you will hear at TFP is stay out of the pool store for their testing. Those numbers could be drastically off which would result in unwarranted changes. We urge all members to have a TF-100 (link in my signature) or Taylor K-2006C for "accurate" at-home testing. It all starts there believe me. from there, we can help. If your CYA is indeed close to 100, your first order of business would be to exchange some water. Then we can help you adjust everything else. Using the PoolMath APP is a great tool. :goodjob: As for phosphates, that's pool store trickery. Ha ha. I haven't tested my phosphates in years, and honestly it shouldn't matter. Don't fall for the bottles of PhosFree or other snake oils. Use your money for a good test kit. When water is properly chlorinated, phosphates are of no consequence.

My water temp is still fairly cool at about 72, but it will rise quickly, so that will impact chemistry as well. See what you can do about one of those test kits and post a full set of your own numbers so we can help you accurately. If you have ANY questions at all, let us know. :swim:

 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
21,234
Bedford, TX
cbj,

I suggest that you go outside and plant a sign in your front yard that says "Algae Party this weekend!!! :mrgreen:

With an CYA of 98 (100 actually) and a ridiculous low FC of 1.. You have a real issue..

Your CYA and FC have to be kept in relation with one another.. See this chart... FC/CYA Chart

The only way to reduce your CYA is to drain some of your pool water..

Thanks,

Jim R.
 

cbj_atx

New member
Mar 31, 2021
4
Austin, TX
Thank you both! I have purchased a K-2006C and a Speed Stir and I've also returned the $95 bottle of phosphate reducer -- it was almost a perfect swap.

K-2006C arrives Sunday so I suppose we'll see what's really going on at that time. Until then, the FC issue has been resolved and is somewhere around an ~11 based on pool math.
 
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Dtkokay

Well-known member
Dec 31, 2019
384
Houston, Texas
Sounds like you’re on the right path. The only additional thing I will say is that it’s better to have your chlorine level a little too high than a little too low, so always err on the high side.
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
16,027
Evans, Georgia
Remember that the sun and swimmers, along with any debris in the water will eat up your chlorine. Each day expect to lose between 2-4ppm, especially in your climate. So make sure you are testing daily adding chlorine to cover the expected loss.

Maddie :flower:
 

HermanTX

Gold Supporter
May 20, 2020
1,577
Katy TX
Pool Size
14600
Surface
Plaster
Chlorine
Liquid Chlorine
the FC issue has been resolved and is somewhere around an ~11 based on pool math.
So long as you keep your FC up in the range of the CYA/FC chart, you can manage to prevent algae. Liquid Chlorine is your friend so have sufficient volume on hand. I normally keep 6-8gals readily available. Keep it in shade or a cool, dry place if possible.

One idea is to watch your weather and if there is a significant storm coming, then drain 6-12 inches of pool water and let the rain fill it back up (may need to top up with your tap water). That is a slower process to lower your CYA valve then just draining a set amount and refilling but doable if you are patient and willing to keep your FC high according the FC/CYA chart.

If you do decide to do a outright drain, then you need to test your CYA and do some calculations to know how much to drain. Understand that you will drain water much quicker than you will add water so need to allocate sufficient time to watch all of this. Also, you need to pick an overcast day so your exposed plaster is not too long in the Austin sun.
Please read Draining your Pool

Draining - Further Reading
Just want to give you some options that I have worked through over the years so you understand the risks and needs.
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
2,115
Spring Valley, NY
CBJ,
You may want to consider SWCG. That'll make pool routine alot easier. I also see you have a single speed 2 hp pump. If and when you upgrade go for one of the VS pumps and save $$ on your electricity bill.
 

iflyjetzzz

Well-known member
Jun 16, 2011
108
Las Vegas, NV
cbj_atx, I'm not in synch with the philosophy that phosphates don't matter. Especially with a SWG. Pentair states that phosphates should be a maximum of 125 in their IC30 salt water generator manual. High phosphate levels interfere with SWGs due to raising the TDS in the water.
If you do opt to lower your phosphates, choose a good product. I use the SeaKlear PhosKlear 4000. 2 ounces per 10,000 gallons; cost for a 32 oz bottle is ~$30. Orenda is also supposed to make a good product. I've been very happy with my 4 year supply (32 oz) of PhosKlear 4000.
After adding 4 oz of PhosKlear to my pool, it fogs up if there is a lot of phosphates in the pool. I run the pump continuously and vacuum the phosphate flakes off the bottom of the pool as the flakes settle to the bottom of the pool. Depending on phosphate levels, it can take a couple of days to get all of the flakes out of the pool. I then clean my cartridge filters. End result is near zero phosphates in the pool.

My opinion on phosphates:
I don't want phosphates in my pool because 1) it is not good for SWGs and 2) it's algae food. Removing the phosphates from your pool removes algae food.
I didn't worry about phosphates in previous pools and had algae outbreaks on occasion when I didn't watch my pool chemistry like a hawk. Now that I use PhosKlear a couple of times a year, I haven't had any algae issues and I don't watch my pool nearly as closely as I used to.
If you choose to not remove phosphates from your pool, you may rethink that after having to SLAM your pool due to an algae outbreak. And PhosKlear 4000 is a dirt cheap way to remove phosphates.
This is just my opinion and you may read opinions that are in conflict with mine. That's OK; my personal experience is that a pool with low/no phosphates is easier to maintain.
 
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wireform

Silver Supporter
In The Industry
Aug 15, 2017
2,115
Spring Valley, NY
Lots of us here aren't checking for phosphates with an active SWCG and don't have issues with algae because a proper balanced water chemistry is all you need. Don't ride the FC at the minimum rather remain at target level or above by a bit and you'll never see algae.
 

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iflyjetzzz

Well-known member
Jun 16, 2011
108
Las Vegas, NV
Lots of us here aren't checking for phosphates with an active SWCG and don't have issues with algae because a proper balanced water chemistry is all you need. Don't ride the FC at the minimum rather remain at target level or above by a bit and you'll never see algae.

There are more than a few posts out there from people with SWGs that stopped working. After lowering the phosphates in their pools, the SWGs started working again.
There are a lot of articles out there about phosphates and SWGs. Here is a nontechnical one: You are being redirected...
There are more technical articles that describe the SWG process and they make clear that phosphates interfere with SWGs.
If you have to increase your SWG output to achieve the same chlorination level, it's likely due to high phosphate levels.
Finally, high phosphate levels void SWG warranties.
 

KevJB

Member
Apr 28, 2021
11
Atlanta, Ga.
Yikes! My SWG failed 3 months after pool install, Aug 2020. No cause was determined and was covered by warranty. What is the most accurate method used to test for phosphates?
My Hayward manual for the TCELL940 doesn’t even mention phosphates - new at this and becoming more confused!
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
37,111
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
If you have to increase your SWG output to achieve the same chlorination level, it's likely due to high phosphate levels.
That is categorically false. Phosphate levels have no effect on a SWCG. Algae in your pool water is the issue. Algae feeds on phosphates. Eliminate the algae by following the SLAM Process, and the phosphates are a non factor.
 
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tplee

New member
May 1, 2021
2
Summerville, SC (lowcountry)
Pool Size
14500
Surface
Plaster
Chlorine
Salt Water Generator
Disclaimer... this is my 2nd post... and as I said in the first, I am and still remain a total pool noob. =[ How many posts does it take to shed the noob status, by the way? ...jk ...forum humor =]

While I am prepared to acquiesce to the experience and recommendations of the site (otherwise, why would I come here, right?)... but first, I have to bring this up:
My pool installer, Blue Haven Pools of SC, does similarly dispels the same pool chemical myths as TFP save one: they highly recommend using Orenda 700 (Enzyme + Phosphate remover). And before anyone brings it up... no, they don't sell it. They told me just to buy it from Amazon. Following his recommendation, I did buy two quarts (64 oz). About 40 oz will be required for the initial dose followed by about 5 oz every week thereafter. Assuming there is no harm in doing so, I suppose I will go ahead and use what I already bought... whether I continue to use it I guess depends on this discussion …

I literally live on top of old phosphate mines here in the Charleston, SC area. A nearby road is actually called Ashley Phosphate Rd. (so named for the phosphate-rich Ashley River that passes within a mile of my house). Granted, I am not sure that these are the same 'phosphates' that we are talking about when discussing pool water. Nevertheless, is it possible there are regional considerations regarding the need for phosphate treatment?

About my pool: just finished installing and filled on April 8th. It is a gunite pool with WetEdge Signature Matrix pebble plaster finish. It is salt-water based, though using regular chlorine for the first 28 days (until May 6th) as per the WetEdge plaster 28-day start-up guide. For what its worth, the startup guide says not to use phosphate remover for first 28 days--of which I will most certainly abide.
 
Last edited:

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
37,111
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Nevertheless, is it possible there are regional considerations regarding the need for phosphate treatment?
If you use your own phosphate test and get above 4000 ppb, then yes, it may be useful to treat for phosphates.

Continuous use of clarifiers/phosphate removes will plug up your filter. So be prepared to change out your filter media, often.

 
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