Black algae or dirt stains

pgershon

Gold Supporter
Jul 15, 2012
281
East Hampton NY
Pool Size
30
Surface
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Hayward Aqua Rite (T-15)
I have a bunch of purple stains on my pool bottom (probably 20 or so in total). Have been there for at least a month. Could be black algae or could be from fertilizer on the nearby lawn getting into pool. I have tried to scrape of some but my nail and a stainless steel brush do not budge the stains, I read that a good test is to rub a tricolor puck on the stain, but I don't use or have any. Is there a cheap way to buy single pucks? All I see are large packs which I will never use.
 

Mdragger88

Bronze Supporter
Jun 1, 2018
2,805
Hernando, Ms
Pool Size
26000
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Intex Krystal Clear
Maybe a neighbor or friend might have one?
also it could be metals issue like manganese. I’m sure some smarter than me guidance will be along shortly.
 

pgershon

Gold Supporter
Jul 15, 2012
281
East Hampton NY
Pool Size
30
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
I out my u/w camera and took a few photos of the stains. Looks like two differ types - one are purplish areas and the others are black dots, almost like dirty calcium deposits on the pool. I cannot budge them however.
 

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pgershon

Gold Supporter
Jul 15, 2012
281
East Hampton NY
Pool Size
30
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
Bumping...

More of these stains visible today in no sun environment. FC has ranged from 7-10 for the last week, although it did drop to 1.5 yesterday (I had turned down chlorine generator) after full day of bright sun. Added liquid chlorine immediately and FC back up to 7. CYN is 70. Stain are not slimy - do not rub off. Hard to say what caused the staining, but it may have correlated with higher chlorine from shock or from adding calcium (taking level from 70 to 375)
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
43,764
Laughlin, NV
Pool Size
6000
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Pentair Intellichlor IC-40
Purple stains are normally copper cyanurate. Have you used copper containing products in the pool? Have you had very low pH or the use of trichlor? Have you had high CYA levels in the past?
 

pgershon

Gold Supporter
Jul 15, 2012
281
East Hampton NY
Pool Size
30
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
My pool company used to put pucks in the skimmers periodically. Nothing put in pool with copper. They used non-copper algaecide ( poly-quant 60). I do have well water. They were running very high pH and TA and very low CA (>8.0, 120, 70). Their services have been terminated . If copper, I am concerned from pool heater, though it seems to work ok.

Staining eally does seem to have gotten worse since I SLAMMED for 6 days and added lots of calcium chloride.

I will get vitamin C to rub this week
 

pgershon

Gold Supporter
Jul 15, 2012
281
East Hampton NY
Pool Size
30
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
One bad thing I know I did was run intellifo pump at 3300 rpm with waterfall on. I just read this can be bad for heater
 

mknauss

Mod Squad
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Bronze Supporter
May 3, 2014
43,764
Laughlin, NV
Pool Size
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Worst thing for a heater is sub 7 pH. Pucks in skimmers, unless the pump is run 24 hours per day, sends very acidic water through the system at start up. But I doubt that would be enough to create your issue. The Manganese angle mentioned earlier is interesting. When you added the calcium chloride, was it dissolved first and added in small batches over many days?
 

pgershon

Gold Supporter
Jul 15, 2012
281
East Hampton NY
Pool Size
30
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
Calcium chloride dissolved in bucket of water and added in four increments. But roughly 3/4 pail at one day. 4 25 lb pails added in total I think.

I remember many years ago (2012 I think) we thought there was a manganese problem and put in metal trap. Pool company has been adding “mineral stain remover “ and billing me for years. That has been stopped.

I am concerned if running pump a lot at 3300 rpm could have done damage.

copper and iron Lamotte test strips both negative (new purchase 2021 so fresh)
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
43,764
Laughlin, NV
Pool Size
6000
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Your heater has an internal bypass and is designed to operate at high rates, so that should not be an issue.

You have an outlier so getting answers / suggestions will be difficult.
 

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pgershon

Gold Supporter
Jul 15, 2012
281
East Hampton NY
Pool Size
30
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
I had my well tested 3 years ago. Iron MDL .04 and my water was tested below. Manganese MDL 0.007 and my well 0.01 mg/l. Looks high, but not crazy high.
 

pgershon

Gold Supporter
Jul 15, 2012
281
East Hampton NY
Pool Size
30
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
The staining is getting worse in the last 3 weeks since I started focusing on the pool. The things I did, of note, were (1) SLAM the pool for 6 days, (2) raise the calcium levels from 70 to 375, (3) lower ph and FA from over 8.0/120 to 7.8/70, raise CYN and stable FC to 70/7.

I am thinking I will drop pH to 7.2 and test with vitamin C (powder coming tomorrow). Assuming this has an impact, do I then try to treat with Jack's Magic Purple? I would prefer not to have to drop my chlorine and not to interfere with the calcium and CYN I have added.

Does this make sense? If the stain test suggests metal, treat for metal There does not seem to be an easy way to distinguish whether I have copper, manganese or iron stains, although I suspect its manganese from the well water (well water analysis a few years ago indicated manganese content above normal).

It looks like my former pool company used to add "mineral remover" a few quarts a month over the last few years.
 

revitup

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Bronze Supporter
Nov 30, 2019
616
Pawleys Island, SC
Pool Size
8500
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
Have you tried a Jacks stain ID kit? It might identify something that will remove it.
 

pgershon

Gold Supporter
Jul 15, 2012
281
East Hampton NY
Pool Size
30
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
I have the kit, been waiting to use it at the same time I try vitamin C. My only concern using it is my FC=7.5. Should I wait to bring that down too? Jacks instructions say FC 1-3.
 

revitup

Gold Supporter
Bronze Supporter
Nov 30, 2019
616
Pawleys Island, SC
Pool Size
8500
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
I have the kit, been waiting to use it at the same time I try vitamin C. My only concern using it is my FC=7.5. Should I wait to bring that down too? Jacks instructions say FC 1-3.
I didn’t and it worked fine, to ID iron anyway.
 

pgershon

Gold Supporter
Jul 15, 2012
281
East Hampton NY
Pool Size
30
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
How did you know it was iron? I see packet 1 and packet 2 etc but I do not see anywhere where they tell you the stain. I thought they did years ago, but not on current product that I can see.
 

revitup

Gold Supporter
Bronze Supporter
Nov 30, 2019
616
Pawleys Island, SC
Pool Size
8500
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
How did you know it was iron? I see packet 1 and packet 2 etc but I do not see anywhere where they tell you the stain. I thought they did years ago, but not on current product that I can see.
I didn’t for sure. I know Jack’s Stain ID kit ‘step 6’ was effective at getting a spot clean and the prescribed ‘iron scale treatment’ was effective at cleaning off all of the stain.
 

pgershon

Gold Supporter
Jul 15, 2012
281
East Hampton NY
Pool Size
30
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
That makes sense. I could find a lot online about copper and iron stains. Manganese seems to be more of a head scratcher. I’ll report what I find.
 

pgershon

Gold Supporter
Jul 15, 2012
281
East Hampton NY
Pool Size
30
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
I did the Jacks stain ID today. Very hard to say what helped. I think the #1 (Iron) helped on the yellowish stain that look like rust. The black stains did not go away, although #2 might have helped a bit. What I did notice is that the black stains in particular are small divets in the Diamondbrite. Looks like the material behind the finish is black tinted. More of a pool finish deterioration issue than staining.
 
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