Strange Stains

Moeqt

Member
Sep 9, 2018
11
Houston/Texas
Over the last two weeks, I have been experiencing brown stains on the pool plaster. I thought it was fertilizer stains, perhaps blowing over from a neighbor yard, and the only thing that would remove the stain is a diluted muriatic acid application directly to the stain. Then, usually each morning, I would come out and there would be new stains. IMG_7385.jpg

At the heart of each stain is a small brown particle. I fished some out today and wondering what they are: is it animal droppings? tree droppings? They do not appear to be anywhere else, but in my pool. For example, they are not on the deck surface, furniture, etc.

IMG_7388.jpg

IMG_7389.jpg

Any help or guidance from someone who has experienced this would be great.

My water chemistry is a whole other kettle of fish as it is out of whack and I was going to post separately seeking help, but I will paste it here. I have had my new test kit for about a month and have taken my readings twice weekly. They have been remarkably stable, but out of whack:

Free Chlorine: 1.5ppm
Combined Chlorine: 0
PH: 7.4
Alkalinity: 100
Calcium Hardness: 500
CYA: it's so high that it is not even reading. On the tester tube, it is at the 19ml mark on the tube, and higher than the highest CYA score.
Saturation index: 0.72

I also have what looks like spots of yellow algae. It brushes off.

Thank you for any help
 
Last edited:

Texas Splash

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Welcome to TFP! :wave: Last time I saw someone post about stains like that, I believe it was determined to be tannin staining from tree droppings. If that's the case with you, maintaining a slightly elevated FC level for your CYA as noted on the FC/CYA Chart may help. If you have any doubt about water chemistry playing factor in this, feel free to post a full set of water test results. We'll be happy to look them over.
 

Moeqt

Member
Sep 9, 2018
11
Houston/Texas
Welcome to TFP! :wave: Last time I saw someone post about stains like that, I believe it was determined to be tannin staining from tree droppings. If that's the case with you, maintaining a slightly elevated FC level for your CYA as noted on the FC/CYA Chart may help. If you have any doubt about water chemistry playing factor in this, feel free to post a full set of water test results. We'll be happy to look them over.
Thank you. I edited my original post and added in my water chemistry and all of my current troubles. I am looking forward to one day being "trouble free". Thanks again.
 

Texas Splash

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To make sure about the CYA test...... are you saying the black dot never disappears? If so, then the CYA is too low (below 30). This time of year your CYA should be at least 40, and when summer temps hit more like 50 with the FC balanced to that CYA as seen on the FC/CYA Chart. On the other hand, if the black dot disappears way too fast as you fill the viewing tube, then the CYA is probably too high (100 or more).

It does look like your FC is too low as well at only 1.5. See FC/CYA Chart. If you are still using tabs and pool store powders, they are driving-up your CYA by the day. That may be part of the problem.
 

Moeqt

Member
Sep 9, 2018
11
Houston/Texas
To make sure about the CYA test...... are you saying the black dot never disappears? If so, then the CYA is too low (below 30). This time of year your CYA should be at least 40, and when summer temps hit more like 50 with the FC balanced to that CYA as seen on the FC/CYA Chart. On the other hand, if the black dot disappears way too fast as you fill the viewing tube, then the CYA is probably too high (100 or more).

It does look like your FC is too low as well at only 1.5. See FC/CYA Chart. If you are still using tabs and pool store powders, they are driving-up your CYA by the day. That may be part of the problem.
The black dot disappears quickly, before I even hit the “high” range of CYA. Is there a link for switching to non calcium chlorine? I realize that I am adding calcium each tome I add this.
 

Texas Splash

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The black dot disappears quickly, before I even hit the “high” range of CYA.
As I suspected. The tabs (and powders) did it. Most tabs increase CYA (stabilizer). Powders can do either. If it says something like Cal-Hypo or shows it on the bag it's calcium. You need neither at this point. First order of business is to lower the CYA, and the only way to do that is by exchanging some water. How much? That's where a good CYA estimate is important. We know your CYA is over 100, so now oyu need to do a Diluated CYA test as noted on the starting at Step #8.

Once you get a diluted CYA test, you can determine your true CYA. For example, if the diluted CYA is 90, your true CYA is 180 (basically Xs 2). To reduce CYA we exchange water. Easy "CYA math" - exchange 50% of water and it lowers the CYA by half. You will want to exchange as much water as necessary to get your CYA down to about 50-60. Do it more than once in stages if necessary. Never empty a pool completely. A CYA of 50-60 is a good summertime range. Once that's done and you top the pool back up, you chlorinate with liquid pool chlorine or regular bleach - same thing. Those have NO CYA or CH side effects.

So you should start there and report back once you've had a chance to lower the CYA. Let us kow if you have any questions.
 

Moeqt

Member
Sep 9, 2018
11
Houston/Texas
As I suspected. The tabs (and powders) did it. Most tabs increase CYA (stabilizer). Powders can do either. If it says something like Cal-Hypo or shows it on the bag it's calcium. You need neither at this point. First order of business is to lower the CYA, and the only way to do that is by exchanging some water. How much? That's where a good CYA estimate is important. We know your CYA is over 100, so now oyu need to do a Diluated CYA test as noted on the starting at Step #8.

Once you get a diluted CYA test, you can determine your true CYA. For example, if the diluted CYA is 90, your true CYA is 180 (basically Xs 2). To reduce CYA we exchange water. Easy "CYA math" - exchange 50% of water and it lowers the CYA by half. You will want to exchange as much water as necessary to get your CYA down to about 50-60. Do it more than once in stages if necessary. Never empty a pool completely. A CYA of 50-60 is a good summertime range. Once that's done and you top the pool back up, you chlorinate with liquid pool chlorine or regular bleach - same thing. Those have NO CYA or CH side effects.

So you should start there and report back once you've had a chance to lower the CYA. Let us kow if you have any questions.
Should I address these little stain bombs as well? Or will lowered CYA help the stains to dissipate?
 

Texas Splash

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Should I address these little stain bombs as well? Or will lowered CYA help the stains to dissipate?
It would be best to address the CYA first so that we can help you balance all the chenistry from there. Unlike pool store recommendations (using tabs, bags of shock, etc), once you lower the CYA and stick to liquig chlorine/bleach, it will never go up again unless YOU want it to on purpose. That's what makes TFP methods so imortant and valuable to pool owmers.
 

Moeqt

Member
Sep 9, 2018
11
Houston/Texas
As I suspected. The tabs (and powders) did it. Most tabs increase CYA (stabilizer). Powders can do either. If it says something like Cal-Hypo or shows it on the bag it's calcium. You need neither at this point. First order of business is to lower the CYA, and the only way to do that is by exchanging some water. How much? That's where a good CYA estimate is important. We know your CYA is over 100, so now oyu need to do a Diluated CYA test as noted on the starting at Step #8.

Once you get a diluted CYA test, you can determine your true CYA. For example, if the diluted CYA is 90, your true CYA is 180 (basically Xs 2). To reduce CYA we exchange water. Easy "CYA math" - exchange 50% of water and it lowers the CYA by half. You will want to exchange as much water as necessary to get your CYA down to about 50-60. Do it more than once in stages if necessary. Never empty a pool completely. A CYA of 50-60 is a good summertime range. Once that's done and you top the pool back up, you chlorinate with liquid pool chlorine or regular bleach - same thing. Those have NO CYA or CH side effects.

So you should start there and report back once you've had a chance to lower the CYA. Let us kow if you have any questions.
Thank you for this. I performed the diluted CYA and found it to be 80. So 160. So looks like about half of my pool water needs to be exchanged. As another newbie question, is there an easier way to empty my pool? I generally hook a hose up to the faucet that sits between the pump and the filter and put one end of the hose into a drain. Is there a link that you could point me towards that would educate me about using bleach vs. the tabs and powders? I have done some reading, but it does not appear consistent. Thanks again.
 

Texas Splash

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is there an easier way to empty my pool?
It depends. People with a sand or DE filter that has a multiport valve can backwash to waste fairly quickly. For those with a cartridge filter, we have to use either a separate hose bib/spigot on the filter (if equipped) or use a separate sump pump to draw water out of the pool. Sump pumps are available for rent at your local hardware store if you don't have one and/or don't want to purchase one just for this.

Once you do some water exchanging and confirm the CYA is back down to earth, somewhere between 50 and 70 hopefully, you will be able to manage the chemistry much better. That's also when you will switch to liquid chlorine and/or regular bleach. Like a pet, a pool gets fed everyday with chlorine. Just part of having a pool, but it's a normal routine once you get started and your water will look much better.
 

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