Black algae or metal stain

[Crazziee]

Hi,
I am a complete newbie to the pool. I purchased a house recently and it came with an in ground pool. The pool was filled but contained some yellow.

I cleaned the pool and the levels back in check. Now I have one issue that remains. I have these stains on my walls and I have no idea what they are. I am hoping its not black algae

[PoolDoc]

I looked at your pictures -- let me show you the color enhanced versions, which often reveals more relevant info:

#1:


#3:


#1 looks like thin plaster that has worn through, and exposed the underlying concrete / gunite.

#2 is uncertain.

#3 looks like possible black algae.

Here's what you need to do:

1. Purchase a cheap local OTO / phenol red drops kit and test your pool
2. If your pH is above 8.0 or below 7.0, post here immediately, with pool dimensions, for further instructions.
3. If your chlorine is zero, begin dosing with 1/2 gallon of plains 8% store-brand bleach* per 10,000 gallons of pool water, added each evening (NOT: morning or midday!)
4. Order a K2006 kit -- see kit info link in my signature -- from Amazon ASAP; report FULL readings here, including CYA, calcium hardness & alkalinity.
5. Meanwhile, operate your pump & filter 24/7

* If you've added copper based algicides, cut that to 1/8 - 1/4 gallon each PM . . AND . . tell us what you added (brand / maker / quantity / pool size).

[Crazziee]

Kit ordered from Amazon, Should be here by Friday.

[PoolDoc]

Hm-mm. Just processed your registration. Look up your address on Google Maps, satellite view.

If Google has your house ID'd correctly, dose your pool with 2 gallons of bleach each PM (or 1/2 gallon, if you've used copper). You appear to have a 16-20x40 modified rectangle with a deep end -- those usually run ~30,000 gallons

[PoolDoc]

Sorry if that sounds creepy -- but I use registration addresses + Gmaps to screen out spammers, before upgrading membership privileges.

[Crazziee]

Thanks for getting back so quick. Those modified images do show a better picture.
Before you responded I did a ph test earlier and it was off the scale, added some muriatic acid to lower.

Once that gets circulated I will take another check. Then update my results.

I am ordering a test kit right now.

Thanks again.

[Crazziee]

Hm-mm. Just processed your registration. Look up your address on Google Maps, satellite view.

If Google has your house ID'd correctly, dose your pool with 2 gallons of bleach each PM (or 1/2 gallon, if you've used copper). You appear to have a 16-20x40 modified rectangle with a deep end -- those usually run ~30,000 gallons

Thanks for checking it out. I have been wondering if the pool store misquoted me when they said it was about 44,000 gallons

[PoolDoc]

Actually dimensions will tell. It's worth measuring it!

And . . . what did the pH test show? Muriatic acid LOWERS pH levels; soda ash / washing soda or borax (Walmart detergent section) will RAISE it.

[Crazziee]

It was higher than my test kit, so over 8.

I will measure the pool now.

[Crazziee]

Wow I was way off. Its 32x16. Excluding the steps.