Phosphates, TDS, CYA, FC TC are high


New member
Apr 12, 2018
Gilbert Az

Just joined the forums. Had a local pool store test my water today:
pool test.jpg

Plaster pool in AZ, Cartridge filter system. Would guess 10-12kish gallons. Have been fighting some green algae on walls (not too much, mostly on south pool wall, annoying to look at). Wire brushed all walls and shocked pool last weekend, 2 gallons of liquid chlorine Friday, 1 gallon Saturday, 1 gallon Sunday. Can see what looks like faint green algae coming back today. Other than that there is a water line on tiles. Pool store guy said today I need to drain and refill my pool. (Last time I did this was 5 years ago when I bought the house). No other chemicals have been in the pool last 6-9 months other than 3" Chlorine tablets.

Would it be best to drain and refill? Also I'm having BBQ Sunday, this water is fine, right? I'm guessing it is but pool store guy said I should have him retest the day before BBQ to make sure it's "ok", not sure why or what that means, maybe because the chlorine is high? Water is crystal clear.

Thank you guys in advance! Let me know if you need any other info.


Bronze Supporter
May 11, 2017
Twin Cities, MN
Welcome to the forum!

A couple things you don't need to worry about in a typical pool are the total dissolved solids and phosphates.

Most people here rely on their own test results because we have found pool store testing to be inaccurate and unreliable. I use the TF-100 from other use the Taylor K-2000c, whichever one you buy look for a magnetic speed stir as well. It makes testing easier/quicker.

Your CYA is typical for someone using 3" tablets. They raise your CYA with each tab you use until it is out of control and you are left with no other option than to drain and refill the pool. It sounds like you don't have a salt water pool so you would want a CYA of no more than 50 in your area.

Here is what I would recommend:
Get/order a quality test kit.
Drain 75% of your pool and refill.
Stick to liquid chlorine or convert to Salt Water pool. In your area a SWG pool really makes the most sense.
Chlorinate your pool according to this chart: [FC/CYA][/FC/CYA]
Read this:
And this: TFPC for Beginners
There is much more info in pool school, link is at the top of this page.

Good luck!


Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
Franklin, NC
First, Welcome to TFP!!:handwave:

That report, like most pool store reports does little to tell the health of your pool. Why, because it is based on pre-1970's science.

The pool industry refuses to recognize the connection between Cyanuric Acid/CYA/Stabilizer (all three names mean the same thing) and the ability of chlorine to do it's thing sanitizing the water. others here can give you the scientific details if you want, but lets just say CYA locks the ability of chlorine to sanitize. The more CYA you have the more chlorine you need to keep in the pool to keep algae at bay.

Think about what the guy is telling you, the chlorine is "high" but algae is still growing? Does that make sense??

As I said, the higher the CYA level, the more chlorine you need to have in the water to keep it sanitary. If we assume that they are even close on the CYA (they are probably low) then your FC needs to be around 20 to sanitize the water. Where did the CYA come from? Most solid forms of chlorine (those tabs you use and the powdered "shock" are almost 50% CYA.

I took over my pool with a CYA of about 250 (CYA tests above 100 are just a guess, not very specific contrary to what the pool store says). With a CYA of 250 I had to keep my chlorine level at around 20 just to keep algae away.

So, my first suggestion is to stop going to the pool store. Their only response it to sell you something.

I will tell you, it didn't get algae overnight and it will take time to clear. But, we can teach you how to get it sparkling and keep it that way for a lot less money than the pool store.

Now, not much credence is given to pool store testing around here. While you would think that a "professional" would be the best, unfortunately in most cases it is quite the opposite. Between employees who blindly trust the word of chemical sales representatives and high school kids working in the pool store for the summer you end up with poor results from their testing. But, what can you do?? We base our pool care system on accurate testing and only adding what the pool needs, when it needs it. To do that you need your own accurate test kit. Order a TF100 test kit and at least include the XL option. That will give you what you need while you are clearing the pool, and probably enough reagents for a couple of years normal use.

While you wait for it to get delivered, you have a homework reading assignment. Start with ABCs of Water Chemistry and Turning Your Green Swamp Back into a Sparkling Oasis

To answer your question - "this water is fine, right?" - No, it's not. If algae is growing then the chlorine level is too low. Can someone get sick? We can't tell you that, all we can say is that there is poor sanitation.

It's your decision. Pool store or TFP. We don't have a magic bullet other than the best pool care chemical there is, chlorine.

Until you have your own test kit that we can rely on the numbers there is nothing we can do other than feel bad about your pool.