Pool got black marks after adding chlorine

E

ebendl

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My father in law stays in Pretoria and has a beautiful white marblelite pool which is usually sparkling blue. This afternoon after the kids had a swim he proceeded to add a cup of chlorine (hth granular+ mineralsoft) as usual.

After a short while we noticed this:
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It is exactly where the chlorine fell. Doesn't rub off with a brush and the kreepy picks up a little of it but not much.

Any idea what this is?
 
chlorine is an oxidiser.if you scrape it with a finger nail does it come off .it may have burnt the topcoat ,or maybe its iron that has leeched trough
 
Very simple. I bet he use Blu 52 or Activator D. That pool has too much metal in it. Have seen the exact same thing at a clients house who only uses Blu 52 for a long time.
So solution is to get a flocculant or metal remover(same thing) and let everything settle at the bottom and then suck it out to waste(not through your filter).
 
Jean Claude Vaaldamme said:
Very simple. I bet he use Blu 52 or Activator D. That pool has too much metal in it. Have seen the exact same thing at a clients house who only uses Blu 52 for a long time.
So solution is to get a flocculant or metal remover(same thing) and let everything settle at the bottom and then suck it out to waste(not through your filter).
Click to expand...
Not the same thing.

Flocculant clears the water by binding fine dirt particles together so they sink.

Metal remover does a chemical thing.

I used to use blu52 but I knew when to use metal remover because the water would go bright green when I added the chlorine.

This looks more like the chlorine scorched the marbelite.
 
Sinbad said:
Not the same thing.

Flocculant clears the water by binding fine dirt particles together so they sink.

Metal remover does a chemical thing.

I used to use blu52 but I knew when to use metal remover because the water would go bright green when I added the chlorine.

This looks more like the chlorine scorched the marbelite.
Click to expand...
Well you can google, there is enough links of using flocculant to remove metal. I used flocculant twice in a short period for a dirty pool and when tested there was almost zero metal in it that I actually used Blu 52 for 2 months just to put back a little metal/copper in the water to help with algae.

As for the black stains. As I said I was literally testing that at my clients house when she asked if I knew what it could be. The hth turned black the moment it hit the bottom. not after a minute or two, immediately.
She told me she used Bly 52 for the last 2 years, we put flocculant or metal remover in, let it settle for 2 days and suck everything at bottom out. She started using HTH floaters and never had a problem since.

So yeah maybe it was just pure luck, but I will stick with my guess.
 
He didn't use Blu 52 or Activator D.

In fact this was the first time in 2 months he added chlorine directly. Uses a chlorine floater in the weir. But he has definitely added chlorine like this before - this is the first time it did this.

What does "chlorine scorched the marblelite" mean?
 
chlorine can burn a surface ,dont do anything rash ,just eyeball it for a few days and keep the water conditions as normal .if its iron which it probably is a treatment of iron remover may work ,iron remover is a dilute hydrochloric acid concoction ,we use iron remover to remove limescale on equipment we use .dont wire brush it or dig on it .marbelite can pull iron from the base layer of concrete or from the ground .marbelite is sometimes sprayed on as a final cement coating .the extra chlorine granuals may have triggered the iron to pop up.so dont panic .give it time to settle
 
soulie said:
pools can do very funky things ,then people panic and throw tons of chemicals and junk in and it becomes a cesspit of horror
Click to expand...
Yup learnt that lesson over the years.
 
My pool just did the same today. Kids seem in the afternoon and I decided to put the blue52 all in one after that as it was looking dirty. It immediately turned black. I’m panicking. And funny is this is not the first time. I always put this blue52 all in one once a week. And I’ve never seen this. I hope tomorrow I’ll also report that it’s cleared itself because right now I’m in panic mode. The marks looks horrible
 
Could it the rainwater causing this? The amount of rain hitting these pools really changes all the chemistry.

I have backwashed for nearly 20 minutes this week and I have a huge pool (120KL) Earlier this week, it was like I had an infinity pool in like 10 mins of rain.

Gonna have to do it again today.

I am just gooiing 4 cups HTH every two days to keep it blue.

Learnt via this forum 10 years ago when I started my pool maintenance journey to avoid blu52.
The only blue 52 product I have ever use is the sparkle cube , and their kreepy until late last year. This week also switched to the Zodiac 6 or something from a Kreepy Barracuda (that had refused to climb walls in the 1 year I had it). Zodiac 6 is pretty good.
 
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