Why is my pool black?

Nov 13, 2009
97
Yesterday I added 8 gallons of 10% bleach with the pump off until the water finished filling and met a black pool this morning. :( :hammer:

Is the black dead algae floating in the water? should I have not added the bleach until I had the pump running and all the water level up to where it should be?

I hope it clears overnight.
 
laurandavid09 said:
To my knowledge, anytime you add chemicals you should have the pump running. Also how did you decide on how much bleach to add?

I read somewhere to add 8 gallons of bleach to shock. I ended up adding 12. (4 more today). I see black dirt like partials floating around (which is the black color).

I have a 15,000 gal gunite pool. Figured since I can't test for CYA I'd reduce water level by 50% and then fill back up and shock 80ppm. also lowered pH with some acid.

I hope the filter clears it up. I probably will need to backwash soon.

I had to do something as the black algae on the bottom was spreading. I get my test kit next week.
 
Is this your personal pool or another customer's?

Is the black stuff you see just floating on top or is it suspended? Is the pool clear or cloudy? What did it look like before you added the chlorine? A picture would be helpful.

You should have waited to have some circulation before adding that much chlorine, especially not knowing what the CYA is. You should at the very least be brushing the heck out of it now that it's in.
 
[/quote]
I read somewhere to add 8 gallons of bleach to shock. I ended up adding 12. (4 more today). [/quote]

I don't think you read that here. I strongly suggest you re-read pool school and learn to use the poolcalculator.com tool. At this point you are just guessing and I'm keeping my fingers crossed for you, but 12 gals of 10% is a LOT OF Chlorine :shock:

Please wait until you get a proper test kit before experimenting and possibly damaging your pool surface.

As for what the black is...a pic would definately help along with a full set of test results :goodjob:
 
spishex said:
Is this your personal pool or another customer's?

Is the black stuff you see just floating on top or is it suspended? Is the pool clear or cloudy? What did it look like before you added the chlorine? A picture would be helpful.

You should have waited to have some circulation before adding that much chlorine, especially not knowing what the CYA is. You should at the very least be brushing the heck out of it now that it's in.

Its a friend of mines pool.

the black stuff is floating and some settles on the bottom by the steps. only part I can see. cloudy I guess and black like oil.

it was clear before I added the water and then the chlorine but there was lots of black algae on the bottom.

yes been brushing lots. going now to check to see how it is. got the pump running 24/7 so want to make sure the filter is not clogging up. will be back later..
 
OMG! 12 gallons of bleach would raise the FC to about 100 ppm in my pool.
Even if your CYA is really high, that is WAY over the amount needed to shock that pool.
That much bleach is definitely not good for the pool equipment.
 
ok good news pool is clearing up. I can see the 3rd step and the ladder and light.

I had to bump the filter. will need to backwash and recharge in the filter in the morning.

I got some 90% trichlor algae fighting ganular if I need it.
 
Well who knows what caused the black/cloudiness and here's hoping it clears up nicely, but here are some things to avoid as you move forward:

1. Don't drain a pool 50% to reduce the CYA when you don't know what the CYA level is.
2. Don't add indiscriminate amounts of chlorine when you don't know what the CYA is, don't have the pump running, and probably aren't sure how much water is in it.
3. If you're adding chlorine based on "something you read somewhere", keep the reference handy so you'll be able to explain to us and the pool owner why you added as much as you did.

Maybe you've explained somewhere other than in this thread why you decided to take this route, but draining someone else's pool because you "had to do something" was irresponsible at best. What you "had to do" was have an accurate analysis of the water. Period. If that means waiting a week then by all means add some sane amount of chlorine, but draining the pool and adding 12 gallons of bleach blindfolded? You're throwing money away and risking someone's property.
 

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