Black Stain on Liner

[Dawgs7]

Over the past couple of weeks, this black staining has shown up on the bottom of my pool liner. It is mainly in the deep end and one little section on the slope towards the shallow end. I put 6 pounds of shock in and it went away for a few hours and came back. I also added Xsorb (sp?), but it did not do anything for the black staining. The local pool company doesn’t know what it is said it could be algae coming from below the liner. The pool is sand based under the liner. Any other ideas?? I have attached pictures of the bottom of the liner along with my last pool level numbers.

 

[Texas Splash]

Welcome to TFP! What I can tell you is that the testing you were provided is not reliable and anything you try right now is close to guesswork. Your best choice of action right now would be to order a proper test kit so that you can be guaranteed of accurate info on which to base your next actions. It may be algae, maybe not, but those numbers won't tell you. We recommend owners use a TF-100/Pro-Series test kit or a Taylor K-2006C test kit. Link in my signature. Start there and then come back and post a full set of your own test results. I'm sure we can help point you in the right direction.

In the meantime, you should be familiar with the TFP SLAM Process and bookmark our Pool Care Basics. Until you obtain one of those kits, consider adding one gallon of liquid chlorine to the water each day. Nothing else.

If you have any questions let us know.

 

[Dawgs7]

Welcome to TFP! What I can tell you is that the testing you were provided is not reliable and anything you try right now is close to guesswork. Your best choice of action right now would be to order a proper test kit so that you can be guaranteed of accurate info on which to base your next actions. It may be algae, maybe not, but those numbers won't tell you. We recommend owners use a TF-100/Pro-Series test kit or a Taylor K-2006C test kit. Link in my signature. Start there and then come back and post a full set of your own test results. I'm sure we can help point you in the right direction.

In the meantime, you should be familiar with the TFP SLAM Process and bookmark our Pool Care Basics. Until you obtain one of those kits, consider adding one gallon of liquid chlorine to the water each day. Nothing else.

If you have any questions let us know.

My buddy has a Taylor Kit and he ran my numbers.

Chlorine - 0.0
CYA - 90
PH - 6.6
Alk - 40
Cal - 340
Phos - 500

Any other information you need?

 

[Texas Splash]

Based on Taylor kit results, I would do the following:
1 - Exchange about 35%-50% of the water to reduce the CYA down to about 50, 60 at most.
2 - Re-test the pH and TA. If they are still low as they are now, then add baking soda to increase the TA to about 70. That should also help allow the pH to rise. The pH needs to make it to 7.2, so follow-up on that for sure.
3 - Lastly, increase the FC to about 7 ppm and run an Overnight Chlorine Loss Test. Let's be sure after all of this there is still no chance for algae.

 

[Newdude]

I put 6 pounds of shock in and it went away for a few hours and came back

It's on your side of the liner, becuase they are impervious.

Mold or algae under the liner will show through on some thinner/lighter liners, but you cannot bleach it away.

My buddy has a Taylor Kit and he ran my numbers

You need your own and need to
SLAM Process with visible algae.

Get some FC in there pronto

 

[Dawgs7]

I drained my pool 15 to 18 inches in the shallow end. Refilled the pool. Added baking soda and borax to get my pH and alkalinity levels right. Then I slammed it with 9# Cal Hypo (53%) on Thursday night. I added a gallon of liquid chlorine on Friday night. I had to wait until today to get the water tested since I don’t have my test kits yet and my friend was out of town. Below are my numbers as of right now.
FC - 0.0
PH - 7.4
TA - 80
CYA - 70
CH - 340

The black stains faded a little after the slam. I dove down and touched them and they are not slimy. But they are back in full force for today. I’m going to dive down and rub absorbic acid on the spots to see if they rub off. I am also seeing tiny piles of brownish something all over the bottom of the pool that when I brush them, they just dissipate into the water.

Any more thoughts!

 

[Texas Splash]

Just add a gallon of chlorine each day. No more cal-hypo. Just wait until you get the test kit for accuracy. But definitely add more chlorine. About 7-8 ppm worth right now.

 

[Dawgs7]

Just add a gallon of chlorine each day. No more cal-hypo. Just wait until you get the test kit for accuracy. But definitely add more chlorine. About 7-8 ppm worth right now.

Absorbic acid didn’t bring up the black spots. Should I try Metal Out?

 

[Texas Splash]

Should I try Metal Out?

I would wait until you get the test kit. Let's be 100% confident of your levels before going down the metals road. All in good time.

 

[JamesW]

It might be something under 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

 

[Dawgs7]

I would wait until you get the test kit. Let's be 100% confident of your levels before going down the metals road. All in good time.

I finally got my test kit in. I ran a test last night and again this morning. I may have read my CYA wrong last night. But here is what I have done. After running my test last evening, I added the required amount of chlorine that it told me to and then I also added a couple inches of water in my pool as it was a little low. I ran the test again this morning and you can see the results. The stains seem to grow and shrink over the last couple weeks as I added liquid chlorine at night. I dove down last week and the closer you get to it with a mask on they look a little more brown from under the water. They are not slimy to the touch. Also the spots that were all over my pool floor and slopes that I thought were mustard algae seem to be sand. I have a robotic pool vac, and when I look into the basket, it looks like dirt and sand mixed together. I did a test last night and left my pool pump off and there are no piles of that sand over the pool bottom this morning. Could there is a hole in my plumbing? My pool is a sand bottom pool so I thought there may be a hole in my liner, but if there was nothing there this morning, would that mean that it is getting blown in through the jets? I appreciate any feedback.

 

[Dawgs7]

A

 

[Texas Splash]

I would first recommend that you update your signature. Some of your questions cannot be answered because we don't know the details of your pool and equipment. The link below should help.

Create Your Signature - Further Reading

www.troublefreepool.com

 

[Texas Splash]

Remind us please, which test kit did you get? That CYA number of 57 doesn't match anything you can get from a TF-100, TR Pro, or Taylor K-2006C test kit.

Also, the pH is definitely high and should be lowered with muriatic acid to 7.8 or below. The FC is very low as well and may be related to the staining (organic). I would use liquid chlorine right away to increase the FC to about 6-7 ppm. Also consider doing an Overnight Chlorine Loss Test this evening.

 

[Dawgs7]

Remind us please, which test kit did you get? That CYA number of 57 doesn't match anything you can get from a TF-100, TR Pro, or Taylor K-2006C test kit.

Also, the pH is definitely high and should be lowered with muriatic acid to 7.8 or below. The FC is very low as well and may be related to the staining (organic). I would use liquid chlorine right away to increase the FC to about 6-7 ppm. Also consider doing an Overnight Chlorine Loss Test this evening.

I bought the TAYLOR TECHNOLOGIES INC K-2006 TEST KIT COMP CHLORINE FAS-DPD.

 

[Dawgs7]

I bought the TAYLOR TECHNOLOGIES INC K-2006 TEST KIT COMP CHLORINE FAS-DPD.

The CYA was between 55 and 60 so I just guessed at 57.

 

[JamesW]

Try a SLAM, but I think that the problem is coming from under the liner.

 

[Dawgs7]

Now, it seems I have more issues. I went to turn my pool pump back on and it’s just hums and then the breaker kicks off. My pump is very hot to the touch.

 

[Nickpooch]

Now, it seems I have more issues. I went to turn my pool pump back on and it’s just hums and then the breaker kicks off. My pump is very hot to the touch.

Literally just had same thing happen. We had a huge heat wave and my capacitor was the culprit. Just switched it out and pump ran right away

 

[Dawgs7]

Literally just had same thing happen. We had a huge heat wave and my capacitor was the culprit. Just switched it out and pump ran right away

So, I got the capacitor off and replaced it and now it’s running like a champ. While I was at the pool store it hit me like a bolt of lightning. I have a hole in the top of my manifold where the pressure has sunk it in over the years. The dirt and sand is not being caught by my cartridges but going right through that hole and back into my pool. I know I’ve had a hole there for the last few years, which is about how long I thought I’ve had mustard algae. I ordered a new manifold and it will be here this week. So I think I solved two problems today. Now I just need to figure out this stuff on the bottom of my pool and I’ll be happy camper again.