New Pool in Texas - Algae or oak stain? Please help

[BlueBell]

Hi everyone,
We've been all over this site looking for an answer to this problem. We have a 5 week old pool with grey plaster interior, 19K gallons, and SWG. We have the test kit recommended on this site, the K2006.

Problem: Spots about 1 centimeter, but varied in ,that are brownish to blackish and circular and most have a smear look to them, similar to a small comet-like tail. Brushing does not remove them.

What has happened so far:
Pool was finished and filled with water and builder put one bag of granular chlorine shock in it, along with 2 jugs of muriatic acid. Builder told us we were all set until salt goes in 3 - 4 weeks later. At 3 weeks we noticed that it was turning cloudy and slightly green. Noticed first spots at this time also. Shocked with 2 bags granular chlorine. Pool and spots cleared.

Salt went in 2 days later and SWG was started. With SWG on at 50% there was 0-0.5 FC in the pool. Spots began appearing again. We assumed algae problem and added chemicals to achieve the following levels:
FC 27 ppm
CC less than .5ppm
PH 7.5
Hardness 180
Alkalinity 85
CYA 60
Copper 0
Iron 0
Salt 3000
Phosphates 500
water very clear sparkling
Pool passed overnight chlorine test.

During shock to 27ppm and constant running of pump all spots disappeared. Assuming we had beaten the problem, we allowed the shock to start to fade. After turning the pump off and the one day fading of the FC to 18, spots began to reappear. Brushing does not remove stains. High chlorine levels or chlorine placed directly on them will work. Vitamin C tablet removed them as well, but they could have just been scrubbed off using the tablet. We aren't sure if it is the same spots coming back or new spots in the same area.

We have many Texas Live oak trees in our yard which are putting out all kinds of things that end up in the pool, due to it being spring. The stuff is coming down fast and we are unable to get it all immediately cleared even though we run our shark, brush, and skim twice daily.

Question: What the heck are these things? Algae, tree tannins? How can we get rid of these?

 

[JasonLion]

If it is possible you should post a picture of the spots.

Your description doesn't match any of the obvious possibilities, though it is close to three of them. Organic stains, which can come from algae or tree debris, won't brush off and fade fairly slowly at high FC levels. But organic stains do not normally come back in the same place. Some kinds of algae (yellow and black) will form spots in specific places that come back even after you appear to have killed them. However, algae will mostly brush off, only to return as soon as the FC level is back to normal. Metal stains tend to appear in the same place over and over and don't brush away, but they normally appear at high PH and/or FC levels and only go away with vitamin C or acid treatments.

 

[Butterfly]

Problem: Spots about 1 centimeter, but varied in ,that are brownish to blackish and circular and most have a smear look to them, similar to a small comet-like tail. Brushing does not remove them.

That describes oak tree junk stain in my pool to a tee! I raise the FC level a little and, like you, try to keep on top of the removal of the droppings. If they are allowed to sit in the pool for even a short period of time, they will stain. The longer they sit, the darker the stain.

 

[BlueBell]

Hi Butterfly,
How do you get rid of them once they are set in? We raised FC level last night to 24 and the pump has been running non-stop. The spots are gone this morning but I'm sure they will come back as the FC fades and we don't run the pump constantly. I will post pics if/when they reappear.

 

[frustratedpoolmom]

What kind of pump is it? does it only have one speed? The fact that they fade at high chlorine levels screams organic. It's unfortunate that with a new pool you need to keep the chlorine level up, but that may be all you can do. I would with a vinyl pool brush, brush the spots when the chlorine is elevated JIC.

 

[Butterfly]

Hi Butterfly,
How do you get rid of them once they are set in?

The oak stains will fade with a little time and increase in FC level. I had the same issue with my new plaster several years ago. Rather than shock the pool, I elevated the FC a little and stayed on top of the droppings as best I could :grrrr: = neighbor's tree

As fpm mentioned, it's always a good idea to brush the spots (vinyl pool brush) when the FC level is up.

 

[BlueBell]

Thanks for all the help.
We have a hayward tristar 1 speed.
What do you think is a reasonable FC number to keep the stains at bay? Right now its in the low 20'S which keeps it clean but I don't think its a good idea to swim in. What is the highest safe (no damage to cloths skin etc.) Fc level for swimming?
Again thanks to you all, when I go to the local pool store they just want to sell me more and more stuff, most of which seems like it will do more harm than good.

 

[crookm11]

Thanks for all the help.
We have a hayward tristar 1 speed.
What do you think is a reasonable FC number to keep the stains at bay? Right now its in the low 20'S which keeps it clean but I don't think its a good idea to swim in. What is the highest safe (no damage to cloths skin etc.) Fc level for swimming?
Again thanks to you all, when I go to the local pool store they just want to sell me more and more stuff, most of which seems like it will do more harm than good.

Hi BlueBell,

You can safely swim in FC levels up to the normal shock level based off of your CYA level. This is a good thread on Chlorine/CYA levels.

 

[Butterfly]

What do you think is a reasonable FC number to keep the stains at bay?
Your Recommended Levelhttp://www.troublefreepool.com/pool-school/recommended_levels for FC is 3 to 5. I suggest the upper end of 5 and see if that will keep the stains at bay. If not, you can bump FC 1 or 2 ppm and see how that does.

Right now its in the low 20'S which keeps it clean but I don't think its a good idea to swim in. What is the highest safe (no damage to cloths skin etc.) Fc level for swimming?
Any FC from minimum up to shock level based on your CYA. Your shock level is about 24, so when FC is below that, you're good to go.
See the link provided by Crookm11

 

[BlueBell]

Thanks for all the help, here are 2 pics of stains that appeared about 2 hours after pump was turned off. Each is about the size of pencil eraser.
[attachment=0:2wse9oo0]pool spot 2.jpg[/attachment:2wse9oo0][attachment=1:2wse9oo0]pool spot.jpg[/attachment:2wse9oo0]

 

[JasonLion]

Are these spots all on the floor, or are some/all of them on the walls?

 

[BlueBell]

All spots are on flat surfaces...steps, bench, deep end corners where tree junk tends to gather. None on the walls. We have tons of them again this morning and I really am starting to think they are from the oak trees. They tend to be more prevalent in the 3 main spots with overhanging branches. I brushed this morning, turned on the pump a little early, and I'm running the Shark vac. We haven't checked our FC yet today but plan to. Hoping there will be improvement with things running. Thanks again everyone for your input. As new pool owners, we really appreciate it!

 

[JasonLion]

Yes, I agree that is sounding more and more like stuff from the tree settling in one spot for a little while and leaving behind organic stains.