Algae returns next day

[drtodd]

Brown patches on bottom of unground vinyl pool. Chemicals are correct. Won't scrub and algaecide does nothing however it is some sort of algae. The only way to get rid of it is dump shock directly on top of it so it coats it. After 10 min, it's totally gone with no stain. Next day it's back in the exact same area. Pool company is baffled and "pool doctor" said he thinks it's coming through the liner not from the water (???) and only way to permanently get rid of it is next time I get a new liner they chemically treat the soil. Anyone heard of this or have any suggestions?

 

[Texas Splash]

Welcome to TFP! There should be almost no reason for any of those agencies to be baffled if the water is balanced correctly and they know what they are testing for. All too many times however, they fail on both counts. So let's start fresh here at TFP with the following questions:
1 - We need to see a full (accurate) set of water test results from your TF-100 or Taylor K-2006C test kit.
2 - How do you chlorinate on a daily basis?
3 - Are you on a well?
4 - This is an inground vinyl pool correct? What type of base was used?
5 - What other misc products (if any) do you add to the water?
6 - Have you tried rubbing a Vitamin C tablet on a stain?

Also be sure to update your signature with all of you pool and equipment info. It helps tremendously.

 

[drtodd]

Welcome to TFP! There should be almost no reason for any of those agencies to be baffled if the water is balanced correctly and they know what they are testing for. All too many times however, they fail on both counts. So let's start fresh here at TFP with the following questions:
1 - We need to see a full (accurate) set of water test results from your TF-100 or Taylor K-2006C test kit.
2 - How do you chlorinate on a daily basis?
3 - Are you on a well?
4 - This is an inground vinyl pool correct? What type of base was used?
5 - What other misc products (if any) do you add to the water?
6 - Have you tried rubbing a Vitamin C tablet on a stain?

Also be sure to update your signature with all of you pool and equipment info. It helps tremendously.

I can answer some now but will get you an accurate chemical print out in a few days.
1) will get
2) 3" pucks - 2 skimmer baskets
3) not on well
4) inground vinyl pool - not sure base but not on cement/concrete (it's spongy)
5) No other products
6) It's not a stain and Vit C does nothing. Vigorous brushing does nothing.
The attached pics are: 1) one of the patches but I have 2 other areas. 2) coating it with shock. 3) 8 minutes later, just lightly swipe it with a brush and it's totally gone with no stain. It will be back tomorrow in exact same spot and the exact same size, color, etc.

 

[Texas Splash]

Pic 1 looks like an organic stain. Pouring some shock (or Cal-Hypo) on it would seem to confirm it. Going back to some of your answers, I would remove the tabs from the skimmer ASAP. They are acidic and bad for the equipment pad. If you must use tabs (and know your CYA can handle them) use a floater. Keep in mind here at TFP we thoroughly enjoy helping pool owners, but not with pool store testing. Free local testing is horrible 99.9% of the time. If you don't already have a TF-100 (link in my signature) or Taylor K-2006C test kit, I would highly encourage you to order one. It should last you all season and save you a lot of guesswork.

 

[Texas Splash]

A couple other things I thought of. How old is your liner? Also, in Post 1 you mentioned using an algaecide. Many of those contain copper and can cause very bad/dark staining. Do you recall what brand of algaecide you used? Have a pic of the ingredients label perhaps? That's something else we need to consider in this verification process.

 

[drtodd]

A couple other things I thought of. How old is your liner? Also, in Post 1 you mentioned using an algaecide. Many of those contain copper and can cause very bad/dark staining. Do you recall what brand of algaecide you used? Have a pic of the ingredients label perhaps? That's something else we need to consider in this verification process.

I live in Pittsburgh and the pool has only been opened for a week however we had this problem all of last season. I was hoping the winter would solve it but the same patches in the same areas were there on opening (lock-down cover). The pics I sent are from today though. The liner is in 5th year. No algaecide has been used since opening so last algaecide was probably August and did nothing. Pretty sure it was BioGuard Algae All 60. I will switch to floater and order test kit.

 

[drtodd]

A couple other things I thought of. How old is your liner? Also, in Post 1 you mentioned using an algaecide. Many of those contain copper and can cause very bad/dark staining. Do you recall what brand of algaecide you used? Have a pic of the ingredients label perhaps? That's something else we need to consider in this verification process.

Also, couple things. It's definitely organic. This isn't a stain. Secondly, if this were a systemic chemical issue, why would the patch return in the exact same spot and same size/shape/color within 24 hrs. (i.e. this is site-specific. If the problem was dispersed throughout the entire pool, why wouldn't I be chasing patches randomly around the pool?) The photo is next day after getting it to disappear using shock.

 

[Texas Splash]

why would the patch return in the exact same spot and same size/shape/color within 24 hrs. (i.e. this is site-specific.

Part of our process of elimination from above with other tests. It's starting to sound smore like you have something from below causing the stain through the liner. That could explain why it keeps returning.

 

[IceShadow]

It could also be a location where there’s less circulation. Water pushes everything together there and it sits, eats up the FC in that localized area, and then you get something growing.

I would also recommend getting a good test kit with titration-style testing, like the ones recommended by Pat, and then doing the
SLAM Process.