Phosphates and Chlorine Levels

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M

mizzamouse

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Silver Supporter
Jul 10, 2017
28
Woburn/MA
Hi, Everyone!

I have just ordered my TF test kit, and it should arrive in a few days. Since I don't have that yet, I am relying on the pool stores water test results. I recently had a huge pool party, and since then the pool water was turning a slight green color and was extremely cloudy. Before I found this forum, I listened to the pool stores advice and added a bunch of overly priced chemicals (Shock, TA increaser, Calcium Phosphate remover, etc...) Since then, the pool has returned to a beautiful blue color; however, the test results are still coming back with low chlorine levels, and off the chart phosphate numbers. The pool store is telling me that because the phosphate numbers are so high, the Chlorine is not able to get to the levels they need to be. Here are the test results as of today (After the shock, super chlorination, TA increaser, phosphate remover and Calcium)

Free Chlorine: 0PPM
Total Chlorine: 0.4PPM
Combined Chlorine: 0.4PPM
PH: 7.5
Hardness: 191PPM
Alkalinity: 122PPM
Cyanuric Acid: 38PPM
Copper: 0PPM
Iron: 0PPM
Phosphate: OVR 4280ppb
Salt: 4250

They are recommending I lower PH, wait 2-3 hours, add 2 quarts of phosphate remover, run the pool for 24 hours, backwash, then super chlorinate.

Thoughts?

Thanks in advance!

--18,000 Gallon Inground Salt Pool - Plaster - Pentair DE Filter - Pentair SuperVlow VS Pump - Built in May 2017 - Pentair test kit - Pentair IntelliChlor Electronic Chlorine Generator - No water restrictions
 
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Here is a link to the recommended levels, notice phosphates are not listed because you don't need to worry about them. Being no one trusts pool store results around here it is really just guess work until the kit shows up. If the pH is correct it is perfect, don't mess with it.

For your size pool you can add one gallon of 8.25% bleach each day until your kit shows up.

And for backwashing your filter do it when the PSI rises 20-25% above the clean pressure.
 
The money you'd spend on phosphate remover would be better spent on bleach.

Interesting bit of trivia.... Phos-free instructions even say not to use it if you have visible algae! Of course they hide that way at the bottom. Phosfree | Backyard Water Care | Natural Chemistry The pool stores ignore that because it doesn't generate the sales they want.

If I believed those pool store results, I'd do nothing but add bleach, following the SLAM Process instructions. To do so correctly requires a better chlorine test than color-matching or pool store testing.

Once your pool is sparkling and balanced and you're enjoying it again, then if you want to lower phosphates -- say you already bought the stuff and can't return it -- that's the time to do it. If you add it while the pool is cloudy, it'll get cloudier to the point that you'll be describing it as milky.
 
Hey, Guys!

The test kit came in! I've been adding chlorine daily while I waited, and was taking my test results to the store for testing. I was planning on following the SLAM process today since I knew the kit was going to arrive this afternoon, so I added 1 3/4 gal of chlorine based on the FC/CYA test results from the pool store. Here are the TFP test results post 1 3/4 addition (started at 4.35FC with .47CC 46CYA from the pool store this AM) That was added this afternoon at 12 PM EST. Given the results, I would assume the SLAM process is complete?


FC - 9
CC - 0.5
Ch - 375
TA - 100
CYA - 30

I do have some CYA that I was planning on adding today since it appears to be a little low.

Given that my FC is below the shock level relative to the CYA chart, should the pool be OK for swimming tomorrow? The water looks crystal clear this afternoon.

Thanks for your help!
 
SLAM and OCLT question

Hey, Guys,

My pool has finally recovered from a chemistry nightmare; however, I don't think I'm out of the water yet.

Before I got my TFP test kit, I was shocked to find that the pool had 0 FC when I took a water sample to the pool store. I was relying on my SWG to supply the correct amount of chlorine even after a party which was not possible. After finding TFP, I've learned a lot about pool chemistry and the proper things to test for (Thank you!). I have a question regarding FC and the SLAM and OCLT process.

On Saturday I shocked the pool bringing my FC levels to 17 (based on 4.35FC and 44 CYA) By Sunday morning, FC dropped to 6.

On Sunday (Yesterday) we had another party. By the end of the day, FC fell to 2! I shocked the pool again last night after the party bringing FC up to about 16. This morning FC tested at 7.


My questions are below.

1.) Should FC be dropping that fast? I'm planning on running an OCLT test this evening until the morning to see if I'm falling by more than 1PPM overnight, but something tells me I probably will considering how fast levels dropped already.

2.) The SLAM process says:

You are done when:

  • CC is 0.5 or lower;
  • You pass an OCLT (ie overnight FC loss test shows a loss of 1.0 ppm or less);
  • And the water is clear.

I pass criteria 1 and 3, however, I am losing a lot of FC during the SLAM process by morning and also the next swim day (I'm not sure if this is normal as stated above). When should the OCLT process happen? The day after the first SLAM when FC is within normal ranges?


I was also going to add some CYA this morning after a backwash to bring levels up to about 50-60, then another boost several days later to reach 70.

Monday's Test

FC - 7
CC - .5

Saturday's Test
FC - 9
CC - 0.5
Ch - 375
TA - 100
CYA - 35
 
Re: SLAM and OCLT question

First, don't add CYa until you pass the Overnight Chlorine Loss Test. If you fail and need to SLAM Process the higher CYA will just make it harder.

I think you are confusing a SLAM Process with "shocking" your pool. The SLAM Process is a process that is continuous, not a one night addition of chlorine. You maintain the shock level of chlorine during the SLAM Process with multiple testing and addition of chlorine. The object is to keep the chlorine at shock level during the entire SLAM Process
 
Re: SLAM and OCLT question

Thanks for the quick reply Tim!

So am I correct in assuming that a SLAM process should span a minimum of 24 hours at shock level and that OCLT should be measured during the SLAM process at high FC levels? If so, wouldn't FC levels stay at shock level (or close to it) for several days by the time it drops down to normal recommended ranges? I'm guessing that's probably OK because it's still safe to swim under shock level?
 

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