Stubborn Black Algae

[Rickhoff]

After reading a bunch of posts; a lot of threads started with emptying the pool... not a great idea here in Houston with our typically high water table. So, please weigh in on metallic vs non-metallic black algaecide, preferred brands, etc. I hear that the metallic version works better but I do realize there is a staining risk, although I have never heard that our water is high in metals (occasional water testing at Leslies over the years).

My plan is hard scrub to remove the protective layer, heavy shock, circulate for 48, vacuum-out dead algae, clean-out DE filter, do the "puck" scrub on the spots, then algaecide, which I'm told needs the CL to be low-ish, circulate for another 48, cross my fingers and resume normal cal-hypo with tri-chlor stabilizer.

 

[mknauss]

Welcome to the forum.
None of what you propose follows what we would recommend.
Please read Black Algae

 

[Rickhoff]

okay, I read the attached link....your plan ?

 

[reggiehammond]

After reading a bunch of posts; a lot of threads started with emptying the pool... not a great idea here in Houston with our typically high water table. So, please weigh in on metallic vs non-metallic black algaecide, preferred brands, etc. I hear that the metallic version works better but I do realize there is a staining risk, although I have never heard that our water is high in metals (occasional water testing at Leslies over the years).

My plan is hard scrub to remove the protective layer, heavy shock, circulate for 48, vacuum-out dead algae, clean-out DE filter, do the "puck" scrub on the spots, then algaecide, which I'm told needs the CL to be low-ish, circulate for another 48, cross my fingers and resume normal cal-hypo with tri-chlor stabilizer.

I'd recommend moving away from cal-hypo and tabs. They're the reason you're in this mess as they're simply an unsustainable means of taking care of your pool.
You need a proper test kit.
Test Kits Compared

Once you have a proper test kit, you can understand the balance of your pool. My guess is you have very high CYA, which renders your chlorine ineffective. You're also likely not running enough chlorine, anyway, as the weekly shock with Calhypo only covers up the problem.

FC/CYA Levels

I assure you, there's a better way. Pool Care Basics
A salt water chlorine generator (best option, or using liquid chlorine, keeps you away from algae without building up CYA or Calcium.

 

[Rickhoff]

Dont I need to get this algae thing under control and get back to the status quo of tabs plus the shock, find a balance ?... then test and I will get a proper CYA test result.

 

[JamesW]

Don't I need to get this algae thing under control and get back to the status quo of tabs plus the shock, find a balance ?

Are you sure that it is black algae?

Black algae takes time to develop.

Was there an extended period of bad maintenance?

Copper stains can be black and many people who have black copper stains think that the black is black algae when it is not.

Can you show pictures of everything?

 

[Rickhoff]

Are you sure that it is black algae?

Black algae takes time to develop.

Was there an extended period of bad maintenance?

Copper stains can be black and many people who have black copper stains think that the black is black algae when it is not.

Can you show pictures of everything?

Absolutely its black algae and not metals staining...pics wont show anything as the water is cloudy post-shock

 

[JamesW]

Black algae does not just pop up overnight; it takes weeks to get really bad.

So, that would mean that the pool was not being maintained very well or not at all.

How long has this black algae been growing?

Has the pool been neglected for a long time?

 

[Rickhoff]

Black algae does not just pop up overnight; it takes weeks to get really bad.

So, that would mean that the pool was not being maintained very well or not at all.

How long has this black algae been growing?

Has the pool been neglected for a long time?

I wouldn't say it was neglected as far as chemicals and brushing go, but it did go through a period without a circulating pump...using the water feature as the only means of circulation (no filtration). Then the cleaner pump went down, and that was well over a month with debris in the pool and no vacuuming, and that's when I started seeing spots on the sides and bottom.

 

[JamesW]

I wouldn't say it was neglected as far as chemicals and brushing go

If you have sufficient FC, then you do not get algae.

If you get any type of algae, the FC was allowed to get too low.

That's just how it works.

 

[duraleigh]

JamesW and others are completely correct. Can you post a set of current test results? I am also skeptical of it being black algae but a pic or pics may help,

We teach things differently at TFP but it's being done on thousands and thousands of pools and it works

Pool Care Basics Archives

Your one-stop shop for all things TFP to include: ABCs of Water Chemistry, Recommended Chemicals/Levels, Test Kits, Troubleshooting, and much more!

www.troublefreepool.com

 

[JamesW]

Also, black algae is not really algae, it is a type of bacteria.

It's actually toxic and people should not use the pool until it is thoroughly eradicated.

It can be eradicated, but it can be a long and difficult process if the bacteria has grown deep into the plaster.

 

[Rickhoff]

Also, black algae is not really algae, it is a type of bacteria.

It's actually toxic and people should not use the pool until it is thoroughly eradicated.

It can be eradicated, but it can be a long and difficult process if the bacteria has grown deep into the plaster.

Toxic... great, gota get in there for the elbow-grease part! I understand the skepticism, but I have seen it first hand. Although CYA hasn't been low according to Leslies's, I will brush, vac, clean the DE and pull another sample for testing again I guess.

Assuming I am correct on the black algae and I do not want to drain the pool, do any of you recommend an algaecide that targets black algae ?

 

[Rickhoff]

JamesW and others are completely correct. Can you post a set of current test results? I am also skeptical of it being black algae but a pic or pics may help,

We teach things differently at TFP but it's being done on thousands and thousands of pools and it works

Pool Care Basics Archives

Your one-stop shop for all things TFP to include: ABCs of Water Chemistry, Recommended Chemicals/Levels, Test Kits, Troubleshooting, and much more!

www.troublefreepool.com

okay, as soon as the water clears I will do some pics.

 

[reggiehammond]

Assuming I am correct on the black algae and I do not want to drain the pool, do any of you recommend an algaecide that targets black algae ?

Algaecide prevents algae, it doesn't do jack once you have it.

I feel like you're missing the message here. You have really poor water sanitation due to lack of free chlorine. The only fix is to improve water sanitation, and balance, and complete the SLAM Process. This requires a proper test kit, and for you to stop using the pool store and their advice.
Test Kits Compared

 

[duraleigh]

+1 what Reggie said.

 

[Katodude]

So black algae is a little different. However, you still need a test kit to deal with it and stop relying on pool store testing.

My latest trick is to use a mask/snorkel and hit the spots with a pressure washer (with full water in the pool). I like it better than brushing with a wire brush, and it is faster and easier. You can also vary how hard you hit the spots.

Then get a 1 gallon pump sprayer (any cheap one from a big box store will do). Fill it with the strongest LC you can find and hit those spots with concentrated LC. Sometimes you can just pour the chlorine right from the jug and let it wash down along the wall to the spots but you use more chlorine that way. But it is easier.

Now the important part, and why you need a test kit. For the next few weeks after you have done the above steps you will need to keep you FC at 20% of your CYA. You cannot trust pool store testing for this.

Now the really important part. Welcome to the BA club. You now have to keep your FC on the high side for the rest of the time you have a pool.