What IS that?

[MEDIC4EVR]

Hello,

Have a 10,000 gallon fiberglass pool and have thick, dark brown buildup along the sides of the pool as seen below.

Pool was shocked 4 days ago.

Whatever it is won't brush off.

FC 0
pH 7.6
Alk 180
Hardness 200
Cya 70

Any help is appreciated!

 

[PoolStored]

What does it feel like when you run your hand over it. Ideas @Texas Splash

 

[reggiehammond]

Algae? - you have no sanitizer in the pool with a 0 FC level.

How do you chlorinate the pool? How do you test your pool water - pool store or a test kit?

If you’re “shocking“ the pool, well, you don’t need to be. The key to TFP methods is ensuring the FC levels never fall below minimum, thus alleviating any need to add excess FC.

 

[Texas Splash]

Hello Medic and welcome! I'm just down the road from you in the Marion area. That is an unusual marking. How far down is that below the waterline? It is true as noted above your FC level is conducive to organics, so there may be some staining, but that seems odd. What chemicals do you usually add to the water? How do you sanitize? Do you use any mineral products or sanitizers? Also tell us what test kit you use. All of this should help us figure out what's happening.

 

[MEDIC4EVR]

It's all basically right above the bottom of the pool where there had been dirt and debris (leaves mostly) from the winter.

I typically use liquid chlorine for maintenance but use powder chlorine shock for shocking.

I take water to pool store if I have time, otherwise use strips.

I've use algaecide. I used MA about a week or so ago to bring down pH. It had been at 8.4.

I recently added Cya as it was down to 0.

Forgot to mention that when I clean filter the water comes out greyish color, like watered down milk.

 

[MEDIC4EVR]

What does it feel like when you run your hand over it. Ideas @Texas Splash

Smooth, slick, and slimy.

 

[PoolStored]

Smooth, slick, and slimy.

It's algae.

Do you have a test kit? If not, get one now. Link-->Test Kits Compared

If you don't, add 5ppm of liquid chlorine per day until it arrives. Brush a couple times a day

If you have one, then start this process...Link-->SLAM Process

The slam process will put enough HOCl in the water to kill the algae. As you brush it, it will break the biofilm on those areas allowing the HOCl to kill the algae. They will come off as you slam and brush (you may have a stain, but we likely can resolve that too).

Don't attempt a slam without a test kit.

 

[Texas Splash]

Along with the test kit, avoid algaecides like the plague. In our region there's no need to close a pool like up north, so algaecides aren't necessary. If you aren't careful, those products can add copper to the water which is a real headache. I've been using a TF-100 since 2013 and I would have it any other way.

 

[MEDIC4EVR]

It's algae.

Do you have a test kit? If not, get one now. Link-->Test Kits Compared

If you don't, add 5ppm of liquid chlorine per day until it arrives. Brush a couple times a day

If you have one, then start this process...Link-->SLAM Process

The slam process will put enough HOCl in the water to kill the algae. As you brush it, it will break the biofilm on those areas allowing the HOCl to kill the algae. They will come off as you slam and brush (you may have a stain, but we likely can resolve that too).

Don't attempt a slam without a test kit.

Thank you. Will begin the process.

 

[PoolStored]

Thank you. Will begin the process.

What test kit do you have?

 

[MEDIC4EVR]

What test kit do you have?

None. I have to order one to begin the process LOL

 

[PoolStored]

None. I have to order one to begin the process LOL

Great. Wise choice. I would recommend the smart stir. Doesn't matter where you get it. It makes testing incredible accurate and repeatable, and even fun and easy.

BTW,