Well this is interesting. Without repeating everything from a post I made as a newbie here, my results from my own pool test, confirmed by a test from Leslie's pool store, gave me decent results on FC, but they tested for Phosphates and that came out at 1500. They said that was high, and risks an algae bloom.

Other results are:

CYA ~ 20 ( was 31 from another pool store) just a couple days ago.
FC: 2
PH: 7.4
TA: 150 (this one is strange, because I tested it myself with a new kit and came up with 80 to 90, and the other pool store told me it was 75 just a few days ago. I only added 4 lbs of sodium bicarbonate, so I see no way in heck did TA go up from 75 to 150 1 day after adding that stuff)

Since this is a brand new pool, and we filled it with water from our local muni on July 20th this year, which gets its water from Lake Michigan, the only thing I can conclude is the water CAME with the 1500 phosphate level.

My water is crystal clear and there are no signs of any algae, so I don't see a reason to spend $80 to remove or lower the phosphate level.

Obviously I need to get the TF100 kit pronto since these pool stores give such wild and random readings. I read it here that other people experience that, and low and behold I am getting the same **** experience.

Heck, they could add all sorts of stuff to your water, or tell you anything they want just to sell you chemicals !

Yup. A good kit is a key to understanding.

And hopefully you have read enough here to realize that the phosphate level is not important ... does not matter if there is food available if the algae can not survive anyway due to the FC.

Correction. The phosphate level registered as 2500 ppb. Parts per billion. They say it should be less than 100 ppb. Parts per billion ??? Give me a freaking break. That's like negligible.

Well, for algae growth the phosphates are often the limiting nutrient and 2500 parts-per-billion (ppb) is the same as 2.5 parts-per-million (ppm) and is plenty of nutrient for algae. However, if you maintain the proper Free Chlorine (FC) level relative to the Cyanuric Acid (CYA) level, then the chlorine will kill the algae faster than it can grow regardless of phosphate level. This is because the algae is also limited in its growth rate by sunlight and temperature.

My Cya is about 30, and Fc is at 2. Will that prevent an algae issue ? and would it hurt to use the phos free to knock the phosphate level down ? Its $50 for the commercial version of 3 liters of the stuff, which should be enough to knock it down to below 100 ppm.

My thoughts are why give the algae all the nutrients if one can knock the phosphates down, especially if the pool currently is crystal clear thus far, and everything else seems to be in line ?

Looks like the phos free will bind the phosphates and catch the particulate in the cartridge filter. Later if the pressure gets too high, i'd likely remove the filters and pressure wash clean.

Ps. Im sort of baffled how the phosphate level got to 2.5 ppm. Its a new pool , less than a month since we filled. No fertilizer use on my lawn since before May, the pool is surrounded by 1200 sq ft of concrete deck, 6 ft privacy fence on 2 sides, house 12 ft away on third side, and we dont live anywhere close to any farms that would be blowing it up in the wind. Tree leafs falling in are very minimal. Maybe a few leaves per day. Use a solar pool cover at night. Im wondering perhaps, if the algaecide my pool builder put in early on, triggered the phosphates ? there is nothing else im using that would possibly have any phosphates, and there are no kids who have any cosmetics on, unless sunscreen has it in it ?

look at the CYA/FC chart in Pool School. 2ppm is the absolute minimum you should let the FC get for that CYA level. Keep it closer to 5ppm.

Forget the phosphates unless you have money to burn. No need to worry about them with adequate chlorine.

Posted from my Droid with Tapatalk ... sorry if my response is short

If the phosphate level was measured by the pool store, they could be wrong. There are phosphates in some municipal water supplies, but not usually that high. Where I live, it's around 300-500 ppb. That will increase over time with evaporation and refill, but I agree with you that the high number doesn't sound right to me (assuming you didn't use a lot of metal sequestrants that were phosphate based, including HEDP).

As to whether to lower the phosphates, that's up to you but it's not necessary. Just think of phosphate removers as similar to algaecides -- not necessary if you maintain proper chlorine levels, but if you want to use them for insurance (at extra cost, of course), then that's your choice. Most people on this forum do not us such extra products. In my own pool I only use chlorinating liquid and some acid but I have borates in the pool (during the season; at the start, I bring up CH, CYA and borates levels since there is water dilution over the winter). Borates are optional and I didn't use them for quite a few years.

Follow up.

Well I tried the Phos free, and it did what it said it would do. My levels have dropped from 2500 ppb, to under 500 ppb with only (2) 1 liter treatments of the commercial strength.

It did cloud up the pool, but it's been 3 days since I started treatment, and 2 days ago since my last add, and the water has been clearing back up on its own.

Other results are:
Water pressure didn't really increase, and I cleaned the cartridges prior to adding the Phos Free.
I did add clarifier last night, and that accelerated the clearing of the particulates. Worked as stated.
Then my water pressure differential on the filter did rise from 18 to around 24 in the next 12 hours. Also as expected. The water now isn't quite as crystal clear as it was before I started the Phos Free process, but it's pretty darn close.

Other stats:
CYA is 40
FC is 4
TC is 4
Ph 7.4 (has stayed remarkably steady, ever since I started testing, and even after adding baking soda)
TA is at 100 (that too has remained steady, after adding 4lbs of baking soda last week, and having a prior reading of 75 before adding the baking soda).
CH is 180
TDS: 200

I sort of expected CYA to rise, because I did slightly turn up the dial to increase the flow through the chlorinator to get FC level up from 2 to 4. The Bioguard 1" silk tabs, has CYA in it.

I'm not messing with this Phos stuff any further, and going to simply let it ride from here, testing as usual and doing nothing else.

I do plan to clean the cartridges over the weekend, and likely install my clean back up set. Seeing the pressure go up is consistent with the coagulation effect from the clarifier, and Phos free getting the phos to adhere to the filter.

The clarifier was a 1 qt for $8 (on sale, half price), and I got the comm strength Phos Free for $50 on Amazon. That saved me at least $40 off from the local store for just regular strength Phos free, for just two bottles, and I would have needed 3 bottles to match the commercial strength, so its probably closer to a $60 savings.

P.s. research on the source of my 2500 ppb Phos level, produced the following:

Unlikely leaves or cosmetics or fertilizers, or detergents of any sort contributed to the levels.
However this is a highly possible source:
My concrete pour for the deck of approx. 1200 sq ft was done during very hot weather. High 90's. So no doubt they used additives to retard the hydration. Additives can include phosphates. Given that rain, and my own cleaning using a hose, kids splashing going in and out of the water regularly, no doubt allowed water to "wash" over the (as of then/still not fully cured and porous) cement, and spill into the pool. Very few leaves, and other possible sources are next to non-existent (that I could think of). And Our source water is about 300 ppb. The cement was the only possible thing anywhere near the pool that I could think of, through a fairly thorough process of deduction.

Set-retarding
Retarding admixtures delay hydration of cement. They are used to offset high
temperature effects, which decrease setting times. Set retarders are used where
delay in setting time is required to ensure sufficient placement, vibration or
compaction time. Set retarders are used in hot conditions or on very large pours.
Set retarders permit application of higher temperature curing of
precast/prestressed concrete without negatively affecting the ultimate strength.
Set-retarding admixtures are the second most commonly used admixture in
highway and bridge construction. ASTM-ASTM C 494, type B is simply a retarding
admixture, while type D is both retarding and water reducing.
Retarding admixtures consists of both organic and inorganic agents. Organic
retardants include unrefined calcium, sodium, NH4, salts of lignosulfonic acids,
hydrocarboxylic acids, and carbohydrates. Inorganic retardants include oxides of
lead and zinc, phosphates , magnesium salts, fluorates and borates. As an example of a retardant's effects on concrete properties, lignosulfate acids and hydroxylated
carboxylic acids slow the initial setting time by at least an hour and no more than
three hours when used at 65 to 100 degrees Fahrenheit.

The use of set-retarding admixtures:
Enables farther hauling, thus eliminating the cost of relocating central mixing
plants; Allows more time for texturing or plastic grooving of concrete pavements;
Allows more time for hand finishing around the headers at the start and end
of the production day; Helps eliminate cold joints in two-course paving and in the event of equipment breakdown; Resist cracking due to form deflection that can occur when horizontal slabs are placed in sections; Some retarders entrain air; Slump loss may increase;
Ultimate strength is improved; Rates of drying shrinkage and creep could increase;
Good for hot-weather concreting; Slow pour rate; and Higher temperature curing of precast/prestressed concrete.
Source links:
http://www.fhwa.dot.gov/infrastructure/ ... tretrd.htm
http://www.admixtures.org.uk/downloads/ ... xtures.pdf
http://www.articlesbase.com/home-improv ... 94095.html

Check your municipal water supply water quality report to see if they add phosphates for corrosion control. They do in my area at around 300-500 ppb so with evaporation and refill, the level will build up over time. At one point, I had over 3000 ppb phosphates (from early use of metal sequestrant products as well) but I prevented algae growth by keeping the appropriate FC level relative to the CYA level.

I don't worry about the level and the only reason it's lower now is that a couple of years ago a guy added phosphate remover and enzymes for free as an experiment (see Orenda Technologies PR-10000 and CV-700 Products). I tried testing the phosphate level this year just to see if it's climbed again, but I measured 0 and then measured the tap water and it showed 0 which I know is wrong so I need to get a new kit since it's apparently gone bad (it's pretty old, so that's not surprising). Given its cost, it's a low priority and I may not get around to doing it since it really doesn't matter.

Our muni, gets water piped to us from City of Chicago, and the source is Lake Michigan. City of Chicago has had endemic pipe corrosion problems for years, and I've heard that they add polymeric treatments that contain phosphates to help stem some of the corrosion. Recently they decided to "triple" all the surrounding villages, towns, and suburbs water rates, so they could replace a lot of the piping. Of course the money will be more than enough just to replace Chicago's own piping, and will be able to line many politicians pockets as well. Of course nobody would dare complain, as getting access to potable water, is one of the country's largest challenges going forward.

Yeah, now that I have an idea of what's happening, I'm not going to worry about the Phos level. I'm just chalking it up to experience as a pool newbie, and I'm one of those people who just has to try things for himself before I truly "learn it" (even if its the "hard way" , lol !)