What in the World???

[Sunbaby]

OK - we have had a LOT of wind and rain and I have a ton of pine trees. When the storms come in, a TON of pine needles and other tree debris fall into the pool and the winds push them to the tanning ledge. This happens 2 X a year and I go out and empty skimmers 2X a day during this time and scoop as often as I can. We have had rain and winds everyday for a couple of weeks. I normally don't use pucks but I have pucks in to help keep up with FC during this mess.

Yesterday evening I went out, tested, scooped, emptied skimmers and went to brush and I noticed brown STAINS on my tanning ledge - in the 2 spots where the pine needles always congregate. No matter how much I brushed they didn't lighten at ALL. So I did my normal stuff and thought I would come ask here today. Also had nightmares last night about ruining my pool! I just went out to take pics of it in the sun and the spots are GONE.

WHAT was it? Any ideas?

FYI - cuz I know you all want to know.
FC 4-7 (It is between 3-4 when I test in the evenings and I up it to 7) I use bleach but also have pucks right now because of all the rain and crud in the pool.
CH 250
PH 7.8 (It raises to 8.1 - about 1-2X a mont I have to add 12 oz of Acid to drop it)
TA 80
CYA 40 (haven't tested in about a month)

Thats weird right? Here is where the spots WERE and it wasn't like you had to look for them - they were THERE and large like 2-5"

[/url]Untitled by Wendy Baldwin, on Flickr[/IMG]

 

[JoyfulNoise]

Picture did not load for me.

Likely tannin stains. They will lighten if you elevate FC for a couple days. Go to shock level. Otherwise you can rub a puck on them to see if it helps but be careful not to damage your plaster doing it that way.

 

[Sunbaby]

The stains disappeared completely overnight. I will have to google Tannin stains! TY

 

[JoyfulNoise]

Oak (particularly the acorns) and pine trees have high concentrations of tannins in them. Tannins are an organic compound found in many species of plants and trees. They typically add an astringent or bitter taste to things. Tannins are found in red wines where an overabundance will give wine a very dry and astringent flavor. Tannins can also be found in ground water due to the decay of plant matter in soil and often leads to brown colored well water. In some areas where high tannin levels are found in well water, specialized pre filters must be employed to remove them from household water supplies.

Tannins will leave a brown stain in pools that responds very slowly to chlorine oxidation. So, if it happens again, the thing to do is to raise your pool water to shock levels and let the higher oxidation rates destroy the tannin stains.

 

[Sunbaby]

Thank you so much!

 

[pooldv]

We have lots of trees dumping stuff in the pool to. I keep a few gallons of bleach around and add a jug occasionally to keep FC up for extra insurance.

 

[Schadenfreude]

If you're using pucks be sure to monitor your CYA levels. They will go up pretty quickly in a pool that size.