Stubborn algae stain

[myschll]

I’m very new at pool care. My husband takes care of the pool. This year he is struggling with what he believes is algae (goes away when shock is put on it, but then returns) that seems to have settled on the pool floor in the shallow end. We have a vinyl liner (28 year old Gunit in ground pool, 30000 gallons). There is a crack under the liner that has been there since we purchased this home three years ago and stubborn algae is in the crack. This has never happened before. Any ideas? He has been using test strips to get chemicals/levels correct, shocked the area directly several times and that stain has lightened but still persists. Any jguidance would be greatly appreciated. I’m asking him to join this forum as well.

 

[mknauss]

Welcome to the forum.
Can you post a picture of the pool and the area in question?
Can you post a full set of pool water chemistry test results from your own test kit? Test strips are not a reliable method of obtaining pool water chemistry data.

 

[woodyp]

Welcome to the forum. I'm a little lost. Is the Crack in the shell....the liner....or liner torn where the crack is? Are you losing water?

You can't fix this issue without one of our recommendedctest kits. Read every link in my signature line while you wait for it to come in.

Any other advice we'd offer will just be guess work, which those test strips have already given you. "Guess" strips we call them.

 

[myschll]

Welcome to the forum. I'm a little lost. Is the Crack in the shell....the liner....or liner torn where the crack is? Are you losing water?

You can't fix this issue without one of our recommendedctest kits. Read every link in my signature line while you wait for it to come in.

Any other advice we'd offer will just be guess work, which those test strips have already given you. "Guess" strips we call them.

I the crack is not the liner …no leaks…we believe it’s a settlement crack under the liner and algae gets in there. We keep making adjustments to chemicals and it seems to be getting lighter but not completely gone. I plan to order the $150 recommended test kit. I will be reading your links. Thank you!

 

[myschll]

Welcome to the forum.
Can you post a picture of the pool and the area in question?
Can you post a full set of pool water chemistry test results from your own test kit? Test strips are not a reliable method of obtaining pool water chemistry data.

I tried to attach a

Welcome to the forum. I'm a little lost. Is the Crack in the shell....the liner....or liner torn where the crack is? Are you losing water?

You can't fix this issue without one of our recommendedctest kits. Read every link in my signature line while you wait for it to come in.

Any other advice we'd offer will just be guess work, which those test strips have already given you. "Guess" strips we call them.

 

[myschll]

I attached a photo. Hopefully you see the line I’m talking about. I am ordering one of the recommended test kits.

 

[mknauss]

A vinyl liner likely has a crease. So dirt, dead algae, etc will pile up along that crease. Or are you implying the gunite is cracked and the liner is somehow compromised by that?

To properly manage your pool water chemistry, you will need to get a proper test kit. See Swimming Pool Test Kits Compared

 

[myschll]

First, thank you for your reply. We believe the gunite is cracked which may have occurred when we had a new bulkhead put in. It’s clay and sand around here so there was most likely some shifting. In a few years we will most likely need a new liner and then hopefully repair the gunite but in the meantime it would be nice not to have an algae stain.

 

[mknauss]

Algae generally does not stain. Stains typically are metals.

 

[myschll]

So, I can test this by putting a Cacium Supplement tablet on it?

 

[mknauss]

For iron, vitamin C tablets in a thin sock. Crush them a bit.
Copper use dry acid.
Only set them on the stain for a few moments. Especially the dry acid.

 

[myschll]

We poor shock right on it and it goes away but next day it’s back.

 

[mknauss]

So Cal Hypo?
If it is algae, it can be brushed away. Can you?
If so, you need to follow the SLAM Process. To do that, you need a proper test kit.

 

[JamesW]

In a few years we will most likely need a new liner and then hopefully repair the gunite but in the meantime it would be nice not to have an algae stain.

30,000 Gallons, In-ground, Galvanized Steel Structure, Vermiculite Interior SurfaceVinyl, test strips, 1.5 HP Hayward Pump, 36 Sq.ft. DE Filter.

Is it vermiculite or gunite?

Most likely it is something beneath the liner.

What are the black stains on the floor of my liner and how do I get rid of them? | McEwen Industries

If you have black or grey cloud-like stains on the floor of your in-ground vinyl liner, they are most likely caused by bacteria that is living in the ground under your pool. Bacteria sometimes show up years after a pool has been installed. We think the bacteria can be washed into your pool area by

mcewenindustries.com

https://www.poolspanews.com/how-to/maintenance/vinyl-liners-tackling-the-toughest-stains-of-all-the-kind-behind-the-liner_o

 

[myschll]

Vermiculite. Brushing makes it lighter but brushing does not make it go away completely. Pouring Shock right on it makes it disappear …did that a couple hours ago so we will see if it comes back. My husband said he has to do something else to it as well. I did order the pro test kit for $150.

 

[JamesW]

If it is beneath the liner, it won't go away until you remove the liner and deal directly with whatever is causing the problem.

 

[mknauss]

@JamesW -- how can granulated chlorine applied on the 'stain' take it away from underneath the liner?

 

[JamesW]

The stain bleeds through the liner and you get some at the surface.

The vinyl is actually saturated all the way through.

Topical applications of chlorine can bleach out the surface organics and maybe slightly penetrate a few micrometers into the vinyl.

 

[JamesW]

It’s strange to think that a 20- to 30-mil liner can retain tens of thousands of gallons of water, but can’t prevent something seeping through from the other side.

What’s leeching through isn’t mere algae.

It’s something far more menacing: Bacteria, mold or fungus. “What differentiates it from algae is that it’s more of a parasitic-type organism,” says Terry Arko, water specialist for SeaKlear Pool & Spa Products, based in Bothell, Wash.

These micro-organisms develop colonies behind the liner and, left unchecked, eventually will permeate through to the printed side, appearing as dark gray or black splotches.

To prevent this, many manufacturers incorporate biocides within the makeup of the vinyl, but this isn’t always a bulletproof solution.

This sort of stain often is misdiagnosed as black algae, Arko says.

Treating it as such, many technicians drop the pH and super chlorinate the water.

Some will even dive down to scrub off the stain with a chlorine tab inside a sock.

The stain will fade.

But don’t expect long-term results.

While high doses of sanitizer will keep subsurface stains at bay, they will return once chlorine levels drop.

Sometimes this is the only way to know for certain that something is festering on the backside of the liner.

 

[JamesW]

Is it okay to leave algae under new liner install?

Hi everybody, If you look back at my other posts and problems you'll see that I had a two trees come down and damage my pool house and pool back in March and April of this year. It's been a fiasco with my insurance company and then trades people since trying to get things repaired. I thank...

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