Trouble with the black algae lagoon

[Elwopo]

Hello. Info first, trouble second maybe? Pool is in ground, plaster, 20,000 gallons, central florida, faces east / west so blasted with sun all day, no screen, hayward vsp pump and cartridge filter, fed with city water.
The issue started with copper staining the bottom of the pool. Used citric acid and was told that chlorine has to be 0 to do so. Got to 0, citric acid worked. In that short time at 0, green algae took over hard. Pool store said blast with chlorine and all will be good. Did so. Green algae went away. Black algae started to appear. Tested the water using the AccuBlue machine and it showed low chlorine so they advised keep putting more in. The black algae only grew larger, now going around the entire pool and 1 ft down.
Yesterday readings: FC 4.67 Total 5.24 pH7.4 Phosphates 3,751 (all other parameters are in line so no need to post)
Used Natural Chemistry Pro supposedly concentrated phos remover. Instructions for my volume and number were to use 8 ounces. Used 16.
Today readings: FC .39 Total .39 pH7.4 Phosphates 3,649 (all other parameters the same as before).
So is there any way possible to figure out what sort of chemical nightmare this is.....or is this doomed to be a skate park?

 

[JJ_Tex]

Welcome, and we see many posters like you every week that have been steered wrong by the pool store. A couple of observations:

• Your test results are clearly from Leslies. Pool stores give terrible advice and have terrible testing.
• Copper staining. I'm guessing that is from algeacide or other blue product which contain copper and not recommended here for your pool for this very reason. Have you used these products?
• You added Phosphate remover. Not terrible for your pool, but pretty meaningless if your chlorine is at the right level and is always pushed by pool stores since it is a money maker
• Your other results are "in line". Can you post them for us? We will still take them with a grain of salt since we know where they came from.

TFP is all about testing your own water, only putting what you need into your water, and we are not trying to sell you anything. Here would be my advice if this site is for you:
1. Stop going into the pool store and get your own test kit. The TF100 is the preferred kit (see my signature for the link) or there are a few others we trust that can be found in the pool school here.
2. While you wait for your test kit to arrive, read up on the pool school. Here are a few articles to start with:

ABC's of Pool Water Chemistry

There are several items things every pool owner should know about swimming pool water. We share details on the basics of Pool Water Chemistry.

www.troublefreepool.com

Swimming Pool Test Kits Compared

What pool test kit should I buy? Why not use test strips? Our recommended test kits will pay for themselves in no time!

www.troublefreepool.com

SLAM - Shock Level and Maintain

We’ve all had to deal with a green pool. Clear algae from your pool with a SLAM! Read here to use shock level and maintain to clear your pool.

www.troublefreepool.com

Black Algae

This guide provides a step by step procedure for eliminating black algae in your concrete or gunite pool. Read full post here.

www.troublefreepool.com

3. Also while you wait for your test kit to arrive, add 5ppm of chlorine to your pool daily using liquid chlorine. For your pool that is exactly 1 gallon of 10% liquid chlorine. My preference is Pool Essentials (Walmart or Lowes) or the Pinch a Penny liquid chlorine (only thing I buy from a pool store).
4. Once your kit arrives, post up your results and we can help you tackle your algae issues.

 

[Texas Splash]

JJ is right, the pool store is your worst enemy. Their advice is horrible, testing I'm sure is off, and products probably responsible for your staining. Once the metals reach a high level, chlorine only makes the staining worse. I suspect a water exchange is in your future, but let's hope you get a reliable test kit first so we can see what's going on. We're glad to help if you let us.

 

[JJ_Tex]

Also I was being nosy and checking out your other posts. In this one from 2014 you seemed fed up with the pool store and said you ordered a test kit. Do you still have the test kit and which one? Are your reagents fresh? Even if not, ordering reagents is still cheaper than a brand new kit.

Cloudy water

Hi, VERY happy to have found this forum. I've been dealing with two pool stores and getting conflicting info. Decided there's no choice but to educate and take charge of this money-pit-pool myself. Bought a K-2006 kit which just arrived. Pool was a swamp 3 months ago before buying new pump...

www.troublefreepool.com

 

[Elwopo]

Update:
The black algae kept growing at an alarming rate. Drained 2.5 feet of water out of the pool. Sprayed straight liquid chlorine using a pump sprayer, twice in 24 hours. Filled pool. The algae in the 'dry' area that was sprayed isn't visible, but there's a slight slimy feel everywhere it was. Attempted to clean cartridge filter but it had a pale blue slime coating the pleats. Soaking in 50/50 chlorine and water then light pressure washing didn't help. New filter going in today.
Test results are from new test kit and a WaterLink spin touch machine. All results from both line up the same.
FC .5 TC 2 pH 7.7 TA 120 CH 130 CYA 20 Copper .4 Phosphates 2000

I'll adjust pH to 7.5 but past that, with the numbers all over the place, not sure of the next step.

 

[MITBeta]

Next step is SLAM Process. What test kit are you using?