Brown stains not from iron

[JimM]

Hello pool experts:
Here's my problem. I have an above-ground pool, 17,000 gal, that I've have for about 15 years. During this past winter (Long Island) I lost the cover, whereas all of the water and debris wound up in the pool. By the time i got around to cleaning it up, around early April, the water was black. I removed much of the leaves, got the filter going, added pounds of shock, added "black algee" stuff, and wound up with a green pool. After more pounds of shock, the water stareded to clear a little, and i noticed that the floor of the liner has stained brown, except for a section in the middle where i still had leaves. Srubbing the floor with a hard bristle brush does nothing. I don't have high-iron water, so I don't think it's iron stains. When i testedthe water last week (prior to pounds of shock) the readings were:
TDS(?): 400
CYA: not tested
Tot Chlorine: 2
Free Chlorine: 2
pH: <6.2
Tot Alkalinity: 54
Optimizer+: 0

I'm running the filter (sand) 24/7, adding a pound of shock a day, and placing 4-5 quick desolving chlorine tablets (2"?) in the skimmer a day.

As you can see, I'm shooting from the hip... any suggestions?

JimM

 

[duraleigh]

Welcome to the forum :lol:

1. Your pH, if correct, is EXTREMELY LOW and needs to be corrected today....bring it up into the 7's using 20 Mule Team Borax.

2. That said, it looks like you are getting pool store tests and they are EXTREMELY inaccurate.

3. The stains are very likely tannin stains (organic) and will lessen and eventually disappear (weeks) IF YOU USE ADEQUATE CHLORINE.

4. Start by reading Pool School (ABC's of Pool Water chemistry is a good one)

5. Make provisions to get enough CYA in your pool to around 30ppm and enough Chlorine to get to about 20ppm. You will use about 5 times as much chlorine as you expect to so don't be surprised.

6. Reread all the basic articles in Pool School and ask lots of questions. If you are ready to take charge of your pool, you will need a high quality test kit.....the pool store tests are inadequate.

 

[JasonLion]

Welcome to TFP!

This doesn't relate to what you asked, but you should get your PH back up to at least 7.2 as soon as possible.

For the stains, there are two simple tests that can help narrow down what kind of stains they are. First, try holding a vitamin C tablet against a stained area for 30 seconds and see what happens. Then try holding a trichlor tablet against a stained area for a minute a see what happens.

 

[JimM]

Dave S.
Thanks for the tips, here's where I'm at.
I adusted the pH as suggested. I changed the sand in my sand filter. The pool is debris free. I've been running the filter 24/7. I also purchased a TFTestkit. As of yesterday, my readings were:
FC 20
CC 0
pH 7.5
T/A 80
CYA 100

The brown stains that I mentioned in my earlier post aren't just spotty stains, but almost the entire floor of the pool is a light shade of yellow/brown, exept for a few spots. When looking at the pool in general, it apprears to have a green tint, but I'm not sure if it is just a reflection of the stain. How would I know if the water is safe for swiming? I'd like to use it this weekend, if possible. Any advice?

JimM

 

[Bama Rambler]

Run an OCLT. If you pass that, your safe to swim.

Did you try holding the vit "C" tab or the trichlor puck on the stain?

 

[JimM]

Run an OCLT. If you pass that, your safe to swim.
Did you try holding the vit "C" tab or the trichlor puck on the stain?
Dave J.
TFP Moderator

Thanks, Dave. Not being a pool care expert (or anything close), I need some explainations. First, what is OCLT? Second, when you say vitamin C tab, do you mean an ordinary vitamin C pill one would take as a supliment? lastly, what do you mean by trichlor tablet? Is this a standard chlorine tablet?

Thanks in advance,

JimM

 

[Bama Rambler]

The OCLT is the Overnight Chlorine Loss Test. It tests to see if you lose any FC overnight. If you do, then there's something eating your chlorine besides the sun and you need to shock. There's a Pool School article on how to do it.

The vitamin C tablet is the suppliment from the drug store, just like you suspected.

The trichlor tablet is the standard chlorine tablet. The 1" or the 3" will work fine.

 

[JimM]

OK Dave, one last question (I hope). You said that
"The trichlor tablet is the standard chlorine tablet. The 1" or the 3" will work fine."
I have quick desolving tablets. Will this work as well?

JimM

 

[Bama Rambler]

Yes, it's the chlorine that we're looking to do the trick, so the fast dissolving will be fine.

 

[JimM]

Dave, I bought a bottle of vitamin C pills yesterday and did the stain test. There was no change using the trichlor tablet but the vitamin c pill reacted almost immediately, as the stain vanished from under the pill. I then filled a sock with the rest of the pills and was able to "paint" clean the pool floor by moving the sock around with a pole. Obviously, using this technique for the entire pool could get expensive and time consuming, so I'm looking for an alternative. I've read something about an ascorbic acid treatment, but couldn't fine the procedure. Is this the right approach? Where can I find this procedure?

Also, my only means of testing the FC is by using the TF-100 Test Kit, as my level is up around 20ppm. I don't know if this is accurate enough to perform the OCLT you recommended above, as this test procedure can be very subjective. How important is it to duplicate the exact amount of R-870 powder? Adding a "heaping scope" doesn't seem very accurate. Will inconsistencies in this addition cause varying results?

Anyway, thanks for all of your help,
Jim

 

[Bama Rambler]

Since the vit C tab removed it, it's an iron stain. Doing the Ascorbic Acid treatment will work. You can use the google search at the bottom of the page to search for it and you'll find how to do it.

The TF-100 is the kit of choice. It doesn't matter how much R-0870 you put in as long as you add enough (hard not to do) it doesn't affect the accuracy of the test.

 

[JimM]

Ok, I ordered 2 pounds of ascorbic acid... keep your fingers crossed. (I'm still a little puzzled as to where the iron came from.) In any event, thanks for your help; I'll let you know how I make out.

Jim