Black Algae Driving Me Crazy

Simple

Member
Jun 17, 2010
5
I have been experiencing a lot of problem with black algae for the last few months. It seems that every time I brushed them away and vacuumed out all the dead algae, it keeps coming back. I even had the crazy idea of bringing my pressure washer into the pool to wash it off. It actually worked but it takes a long long long time so here I am seeking for help.

By the way, I had the same problem last summer and a pool service guy came by and dump a load of chemical into the pool and after some vigorous brushing, the stains were gone. He told me that it shouldn't be back if I put 2 pucks in the skimmer every week and do some light vacuuming. I did that until we had to close the pool for the winter. We opened it up this spring and the problem is back.

I would do the same thing again except I don't want to repeat this every year. Is there some way that I can get rid of it once and for all? Like draining the pool and power washing the whole thing? I have a cement plaster pool. I only have a few hundred dollar budget to get this thing over with.




Thanks guys.
 

waskydiver

LifeTime Supporter
Jul 29, 2009
191
If you follow the BBB method, you can probably get the problem resolved, and have enough money left over for a party within your budget.

We first need your test results:

FC (Free Chlorine):
TC (Total Chlorine):
pH:
TA (Total Alkalinity):
CYA (Stabalizer):
CH (Calcium Hardness):

Also might be helpful if you provide an inventory of chemicals you have on hand.
 

dmanb2b

TFP Expert
LifeTime Supporter
Apr 4, 2009
3,734
NY
Welcome to TFP...your algae issue is most likely due to inadequate FC levels. Your solution may be as simple as shocking the pool.

1st you will need to post us some test results and read through pool shcool on how to defeat algae

we'll nee the following measurements

FC
CC
PH
TA
CH
CYA

and any pool specifics you can provide
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,880
Silver Spring, MD
That doesn't look like black algae to me. When you touch it, is it slimy? Can you scrap any off with your finger nail?
 

Mr. Ed

In The Industry
Jun 16, 2010
38
Dallas Tx
JasonLion said:
That doesn't look like black algae to me. When you touch it, is it slimy? Can you scrap any off with your finger nail?

agreed...looks like some sort of stain.

the chemicals added in the past by the pool guy may have temporarily bleached these stains, or the source of the staining is still in or being added to the pool by a nearby source.
 

bk406

Well-known member
Dec 3, 2009
2,690
Central Massachusetts
Have you ever used an algecide that contains copper? Maybe pucks that have copper? Could also be manganese. Try holding a vitamin C tablet on the stains and see if they lighten up any.
 

Simple

Member
Jun 17, 2010
5
thanks guys for the feedbacks. I will get my water tested tomorrow.

I can't scrape it off with my finger nail and it's not slimy. Does that mean it's not black algae? I am able to scrape it off with wire brush. However, it comes back very fast after a few days of rain.
 

geekgranny

LifeTime Supporter
Aug 20, 2009
1,358
North Central Texas
Welcome to TFP. :wave:

I would expect that if it is metal staining it would be on the step too. Note that it is on the uprising to a step but not the step. How is your circulation near the steps?

gg=alice
 

Simple

Member
Jun 17, 2010
5
Hi, sorry guys for the late reply.

I used my own kit to test the water, I'm not sure how accurate they are though.

FC >1 ppm
CC >1 ppm
PH 6.8
Hardness 100ppm
Alk 20 ppm

I'm not sure about the stabilizer, it wasn't included in the kit :(
Also, the black spots are only on the uprising of the steps because I pressured wash the rest off. It took a long time though.

The tiles around the water mark are falling off, do you think it has anything to do with the water content?
Also, would it be wise to drain the pool and pressure wash it? The water hasn't been changed for a really long time, about 10 years I think, and so tiles are falling off. So I want to replace it and maybe paint the pool a different color so it will look cleaner.

Thanks again.
 

Simple

Member
Jun 17, 2010
5
JasonLion said:
Definitely metal stains. Try the vitamin C tablet and see of that has any effect.
Do you mean any OTC vitamin C tablet? Or is there a special product for pools? Sorry I'm fairly new to this.
 

Butterfly

TFP Expert
LifeTime Supporter
May 30, 2007
10,045
South Carolina
Simple said:
JasonLion said:
Definitely metal stains. Try the vitamin C tablet and see of that has any effect.
Do you mean any OTC vitamin C tablet? Or is there a special product for pools? Sorry I'm fairly new to this.
Yep, an OTC vitimin C tablet. Hold it on the stain for at least 30 seconds to see if the stain lightens or disappears.
 

Simple

Member
Jun 17, 2010
5
Butterfly said:
Simple said:
JasonLion said:
Definitely metal stains. Try the vitamin C tablet and see of that has any effect.
Do you mean any OTC vitamin C tablet? Or is there a special product for pools? Sorry I'm fairly new to this.
Yep, an OTC vitimin C tablet. Hold it on the stain for at least 30 seconds to see if the stain lightens or disappears.
I did the vitamin C tablet test and there were no noticeable improvements. It's pretty dark outside though, so I'll try again tomorrow.
 

frustratedpoolmom

TFP Expert
LifeTime Supporter
In The Industry
May 20, 2007
12,177
SWSuburban Chicago, IL
Yes, your PH and CH are both too low.
I don't necessarily think this is metal - it doesn't sound like it based on your description.
Hold a trichlor tablet on the stains and if they fade, they are organic in nature.

Your CYA/stabilizer level is key to knowing if you are maintaining a proper FC level. Consistently low FC will allow organics/algae to get hold and that could be what you have here. It could also be copper staining which the Vit C may not have an affect on.

I suggest trying a trichlor tablet on the areas and see what happens there.
In the meantime adjust your ph up to the mid 7s asap. The CH can wait until we resolve this other issue. :)
 

cannonball.pools

In The Industry
Jun 22, 2010
2
Sadly, you can never get rid of Black Algae. It's a pest. You can do things to keep it at bay, but you can never get rid of Black Algae.

Sorry
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
31,680
Sebring, Florida
Well, I have doubts about "never".

I know it's very tough but I'm sure you can keep it from ever bothering you with proper water management.

I have a vinyl pool and have never gotten it but I believe a continued long (perhaps a couple of seasons worth) exposure to high levels (but swimmable) of FC would probably do the trick.
 

frustratedpoolmom

TFP Expert
LifeTime Supporter
In The Industry
May 20, 2007
12,177
SWSuburban Chicago, IL
cannonball.pools said:
Sadly, you can never get rid of Black Algae. It's a pest. You can do things to keep it at bay, but you can never get rid of Black Algae.

Sorry
Sorry to contradict, but we've had many members successfully beat Black Algae.
 

geekgranny

LifeTime Supporter
Aug 20, 2009
1,358
North Central Texas
A word on Vit C tabs. DH buys the vitamins and puts them in a container so I don't always know what brand they are. He doesn't often look at prices. He had gotten some that seem to be denser and have a more "polished" exterior, like a glazing almost, that takes forever to dissolve in my pool. Others have dissolved more readily.

The "coated" one actually leaves yellow goo at the spot where is is placed and has to be brushed off.

Just wanted to let anyone know about that. Sorry I can't give a recommendation for the best Vit C to use but probably the most costly one (which is probably what these "coated" ones are) might not be the best to use for stain testing in the pool.

When I did my first stain test, last summer, the Vit C tabs dissolved totally in about 10-15 minutes. These "coated" ones may not even start appearing to dissolve for 20 minutes, or more, and then turn into a tan/yellow blob.

gg=alice
 

geekgranny

LifeTime Supporter
Aug 20, 2009
1,358
North Central Texas
Green, black, yellow algae are opportunistic, just as many disease causing agents are. They just hang around waiting for the chance to "invade" when resistance is lowered.

For instance, if I have a bad upper respiratory allergy to something, approaching anaphylaxis or anaphylaxis, thank goodness not too frequently, I, more often than not, get some kind of viral infection, usually upper respiratory, sometimes a cold and occasionally a full blown flu. I'm not "infected" all the time by these viruses, but they certainly are hanging out somewhere near by waiting to get me.

Of course black algae can be killed. You just have to get through the outer barrier so the killing agent will kill it. Quat algaecides don't kill the algae, or so I have read, they just assist in wetting the barrier so that the killing agent, chlorine, for instance, can get into the cells, to then kill.

gg=alice
 

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