dark green water

2nd year pool owner, 1st year opening from winter.

Took winter cover off yesterday to find pool in a full algae bloom. Very dark green and cloudy. Barely see bottom in shallow areas. What would be the best way to treat.

Already put some algaecide in pool, and 4 gallons of 12% bleach, and 2 gallons of 10% bleach. Ran filter overnight, no change. Plus vacuumed early this morning on waste mode on filter.

Above ground pool
27,800 gals
sand filter - new sand from opening of last summer
Taylor test kit - reagents from last year but bought in August and used for hot tub over winter.
Chlorine # is higher then test kit goes which is 5
Ph 7.2
Total alkalinity 90

Hello... I'm newbie here so I'm not going to be much help but wanted to say that I sympathize with you. My situation is similar to yours (albeit, with a smaller pool... 28k gals is huge!), I'm fighting the algae enemy!

I'm also failing to see improvements after shocks.. but my understanding is that we have to keep at it, since it can take easily a week in some instances before getting significant improvements (?). Seems to me that you are doing all the right things.

Do you know the amount of stabilizer (CYA) in your pool? My understanding is that, although it definitely helps maintain a high level of Cl, this can also greatly limit the sanitizing effect of Chlorine if it is too high... Might be worth a look!

Hi Becca;

If you would, please give us complete info about your pool here:

Pool Chart Entry Form
Pool Chart Results

Also, as Nick correctly noted, we need to know your CYA level, and also your calcium level, before we really dig in.

Meanwhile, using bleach is the safest way to chlorinate, since we do NOT know your CYA or Calcium levels. Reasonable doses on your pool would be 8 gallons of PLAIN 6% household bleach, or 4 gallons of FRESH 12% commercial bleach, added each EVENING, till the pool changes color. Once it does, add another 8 gallon dose and then
EITHER
+ brush to stir up any algae piles on the bottom,
OR
+ carefully vacuum the pool to waste.

But, you do NOT want to stir up that algae, till you've killed what's floating AND have a high chlorine level in the pool. Particularly if you brush, you may have to add 8 gallons before you brush and then 8 more AFTER you brush.

Hi, Becca! Just wanted to welcome you to the Pool Forum! We'll help you get that pool cleared up and get you swimming!

My calcium level is 140 and CYA level is 20. No difference in color of pool since original post.

Hi Becca;

I looked at your pool chart info. I'm not sure who gave you the volume figure on your pool, but it's almost certainly incorrect. Assuming you have a deeper than average AG pool (54") with an actual water depth of 48", and a 28' diameter, your gallons are about 18,500, and your PF is 6.5.

What I need you to do, tomorrow evening I guess, is put 10 gallons of PLAIN 6% household bleach in your pool, and THEN test the chlorine level the next morning, before 9am, using an OTO (yellow drops) test. If the chlorine level is lower than DARK yellow, repeat the dose (10 gallons) that evening, and test again the following AM. Also BEFORE you add the bleach the first time, put in (4) boxes of 20 Mule Team borax (added slowly, via the skimmer, with the pump running).

So . . . when you go to Walmart or Kmart or wherever, you need to get:
+ (20) gallons of plains 6% bleach (check the %) or 27 96oz bottles
+ (4) boxes of 20 Mule Team borax
+ (1) OTO / phenol red kit. (Get the HTH 6-way drops kit, if your Walmart has it -- excellent value)