Need help to identify algea

[Sthlm:are]

Hello I'm having trouble sorting out what som "rust like" stains are. I've attached a few photos and was hoping someone in the forum could point me in the right direction.

(I've tried to rub both ascorbic acid and cal hypo on them but with no real effect. The ascorbic acid turned the test spot black temporarily but then got back to rust color again after a few hours???)

Thanks in advance
Martin

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[duraleigh]

Welcome to the forum

Since the ascorbic acid had no effect, I think you can assume it is not iron.....although it has that c olor.

Have you placed a tri-chlor puck on the stain for a few minutes?

 

[Patrick_B]

Welcome to TFP from Texas!!

 

[Sthlm:are]

Only tried rubbing with cal hypo pucks not tri-chlor.....

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[Sthlm:are]

Thanks for the warm welcome, I've been a frequent reader for a few years however this might be my first post.

I'm from Sweden by the way ?

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[zea3]

This is a tile pool?

 

[Sthlm:are]

This is a tile pool?

Yes it is

 

[zea3]

You could have rust in the rebar structure of the pool that is bleeding through to the surface. The usual stain removal techniques won't fix this problem. I'm not sure this is the cause of your stains, however. Ascorbic Acid will turn copper stains black. Have you ever used any copper based products in your pool? How old is the pool?

 

[Sthlm:are]

-The pool is 3-years old.
-Rebar rust is not likely since the pool has a waterproofing membrane between the concrete structure and the tiles.
-Early in the season I used a cal hypo from a Swedish manufacturer, but their product should not have any copper in it. I need to double check that. However only used their tablets for like 3-weeks until I got my automatic dosage system up and running.
-The pool is filled with "drinking quality" water from our municipalty's residential water system (should not contain any metal as far as I know)

I could double check the copper theory hands-on on some stains, but what typ of product should I use to remedy copper stains then?

 

[zea3]

Do you have a heater with a copper heat exchanger, or any copper pipes in the pool plumbing? Copper stains are difficult to remove, but if you use sequestrant and keep the pH around 7.2 the stains should fade over time. I would also ask the builder to inspect the pool and offer an opinion for the stains.

 

[Sthlm:are]

No the pool heat pump has a titanium heat exchanger, and all pipes and fittings are PVC....

What typer of sequestrant would you suggest?

 

[zea3]

Sequestrants based on HEDP, phosphonic acid, or phosphonic acid derivatives are the most effective. I don't know what brands you have available in Sweden, but Pro Team Metal Magic or Jack's Magic: The Pink Stuff are a couple of the brands we recommend.

 

[Sthlm:are]

Ok thanks just ordered 3-liters of a european brand "Delfin metal magic" it's active component is diphosphoneacid.

Will try and report back.

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