Black Algae in a vinyl pool?

[colemast]

Black Algae is round, small dots like the size of eraser and they spread out in a circular way, green algae is more suspended in the water but will also cling to surfaces. Mustard Algae is similar to green algae but it is more resistant to chlorine, and often it takes prolonged periods of higher FC and brushing to keep mustard algae at bay. Mustard Algae tends to like shady areas of the pool. Black algae is also resistant to chlorine, and it takes frequent brushing with an appropriate brush, with FC at shock level to kill it. It can leave behind nasty stains. It is very rare if not unheard of in a vinyl pool.
If you have stains in your pool and post them, we may be able to help identify them.

Pool water is now crystal clear thanks to you guys. Switched to BBB and it's looks great - except I have a vinyl liner which I believe has black algae. There are only about 5-10 spots smaller than a dime (eraser head) I have brushed scratched and rubbed with no luck. Now after a couple of days the bottom has black areas that I can easily brush but I concerned. I am having a hard time keeping Chlorine level up. CYA = 30. PH=7.5 Chlor= 3.5 to 6 but drops to near zero in less than 2 days. I burning through 8-12 gallons of bleach every other day. The pool store sold me a 32ounce bottle of algaecide (Bioguard) and they believe it is black algae. But it has not gone away. I'm using a nylon brush vacuum head.

What is an appropiate brush for black algae on vinyl?
Can black algae be my Chlor level problem?

 

[frustratedpoolmom]

Nylon bristle.

Any chance you can post a pic? I have yet to see a confirmed case of Black Algae in a vinyl pool, in over 2 years of being on the forum. YOu can hold a trichlor tablet on the black stain and if it fades, it's organic. That doesn't mean Black Algae.

Even if it were Black Algae, chlorine would be prescribed, not algaecide - which is more of a preventative than a killer. Don't use it.

How are you testing the water? I'd be concerned about the accuracy of the CYA level.

Is your FC holding overnight? If not, that would explain why you can't keep the FC up, and it means you need to shock the pool.

Black areas "easily brush"? Do you mean dusty/dirt that brushes away and returns? That's not black algae either.

So lets clarify the missing pieces and figure out what's happening in your pool.

 

[colemast]

I'm testing with Leslie's kit and confirming with local pool service.

I will try and get an underwater picture (this Friday).
I also don't believe I'm holding my Chlorine level either. This past weekend I got it up over 8.2 (store tested) but it was below 5 by in the morning and down to 3 by the afternoon.

too late on the algaecide though - 32 ounces put in last Friday.

On the black areas (agree dirt) I use to get the white to grayest remains of powder (Bioguard Extreme 2) This probably just masked what I'm now seeing.

Here's the best description I can give on black spots: very small but visible due to crystal clear water, some brush away after vigoruos scrubbing over and over, some spots I've altered with my fingernail (looks like it smeared) and some spots I'm able to scratch off fairly easy with fingernail. The color from out of the water looks black but up close with goggles it's a very dark blue-black-green (is that even a real color - picture a blue-green that is very dark.

5 year old 30' round 1.5HP 250#Sand 54"deep vinyl
(new pump/motor & sand)

Thanks for all of your help and knowledge. I'm already happy to have switched from Pool Store$$$$ to bleach - even looks clearer than ever before.

 

[frustratedpoolmom]

Hmmm. That's a very odd description. But thorough. Can't wait to see pics.

Okay, you should go ahead and shock your pool, if your CYA is 30 then shock it up to 12. This means hold the 12 FC, by testing often as much as hourly to ensure the number is holding. Then perform an overnight FC loss test so we can confirm if you have live organics in the water (sounds like you do).

I'm assuming your Leslie's kit is the re-branded K-2006 that has the FAS-DPD chlorine test? You'll need that to do the overnight loss test.

What was on the active ingredients in the algaecide? Some algaecides great a high chlorine demand which may be contributing to the problem.

At least the water is clear

We'll help you get this straight, no worries

 

[colemast]

Bioguard Back Up
Ingredients
Alkyl dimethyl benzyl ammonium chloride 30%
Dimethyl Benzyl Ammonium Chloride 10%
Other Ingredients 60%

My Leslies kit only goes to 5.5 FC -

Can live organics be invisible to naked eye - The water is beautiful.
And after I vacuum 99% of the people won't even see the black dots
I'm worried about. I'll try and do as you say - Here comes the bleach.....

as always thanks
Shanon

 

[frustratedpoolmom]

Yeah, the algaecide is junk, and will increase your chlorine demand at first. Won't do a thing for the spots.

You should really consider supplementing your kit with the FAS-DPD test.
http://www.tftestkits.net/index.php?act=viewProd&productId=23

 

[colemast]

I'll check into the test kit you mentioned.

I am definately losing chlorine - this morning back to zero. I just adding 6 big bottles of bleach (182 oz? each) The chlorine level is super purple. I'll have actual numbers checked this morning at pool place. I vacuumed pool this am and water is still crystal clear and sparkling - but the black spots remain (middle of pool - probably where less circulation is happening). I removed 2 plastic floats and I beleive I have found what it possibly the spots at the bottom. See attached photo. This stuff is super sticky like tar. after I rub it it transfer to my fingers and feels like tar. The floats were trapped against pool side and stair handrail and this stuff is growing at water line facing the discharge current.

These floats were in the water for they last 5-6 days with the Bioguard Back Up algaecide - which of course did not help the back spots nor this fungus looking stuff.

Now for some bad (good news?) - I won't be able to play with this pool after today because I headed to Cocodrie La to catch some specks & redfish and I won't be back till Sunday.

My current plans are to get actual level of chlorine - (twice today - and add more tonight before I leave) Any thing else I should do?


Shanon[attachment=0:3a06f9ak]PoolFloat.jpg[/attachment:3a06f9ak]