Brown stains spreading

[tmmort]

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If you keep the pH between 7.2 - 7.4 (it keeps the metals in solution) you should not have too many stain problems. Keep the REAL alkalinity between 90 and 100, this to helps keep the metals from falling out of solution, using your CYA number to adjust this. Example a CYA of 60 X ph 7.4 adjustment of .33 gives a reading of 19.8. So your alkalinity should read 120 on your test kit to get a real alkalinity of 100.2. At a CYA of 40 the adjustment is 40 X .33 or 13.2 so your reading should be around 110 to get a real count of 96.8.
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I've never heard of this relationship between CYA/pH/TA. Can you elaborate and/or post link that explains this? Thanks!

[waterbear]

You can get ascorbic acid which is vitamin C, or there are other products that use oxcylic acid? I am not sure if that is the right spelling.

Marie, very close...oxalic acid is the correct spelling. And ascorbic acid is less toxic so it is my first choice also.

[TheNewPoolGuy]

You will probably have to do a stain treatment. You are using a product that is probably a sequestering agent - it will bind with the metals that are suspended in the water, but if the stains are embedded, they will not lift off with just the sequesterant. You can get ascorbic acid which is vitamin C, or there are other products that use oxcylic acid? I am not sure if that is the right spelling. I always use the ascorbic as it is the most mild. Here is a link to buying it cheaper than the regular pool products.

http://www.msm-msm.com/store/agora.c...scorbic%20Acid

http://www.chemistrystore.com/Ascorbic_Acid.htm

If you chose to do this treatment, I can give you directions on how to use it.

Marie:

I have a similar problem. I have an AG Doughboy 12' X 20' pool, 8,200 gallons. I live 15 miles West of New Orleans. I have been fighting staining problems since Hurricane Katrina. My readings are:

FC - 3.0
TC - 3.0
PH - 7.5
CH - 160
Alk - 130
CYA - 50

I have brown stains that are on the bottom of the liner. I have tried a product called Pool Stain Treat by United Chemicals. The active ingredient is Oxalic Acid. I was told to add one quart of EZ-CHLOR, Metal Magnet. I was told to shut down the pump long enough to have the water completely idle. Mix 1 pound Pool Stain Treat to 4 gallons water, mix well. Then, get a 16 ounce cup and gently pour the mixture into the pool over where the stains are. The mixture is heavier than the pool water, and you can see it going to the bottom. When it hits the stain, most of the stain is removed and the water gets cloudy. You continue this process until all the mixture is gone. By the time you finish, the pool is cloudy and you will have to start the pump and shock pool. I used 2 lbs of the Pool Stain Treat and it worked well. I still have some stains and I am waiting for the ascorbic acid I ordered. I am told that you are suppose to use the same process with the ascorbic acid. I hope thjis helps. If you have any other ideas to help me reomove the rest of my stains, give another post. I am ordering the new kit, PS234 and hoping to run all my own samples.

[mbar]

When I used the ascorbic acid I didn't dilute it in water. I just poured the ascorbic acid down the walls of the pool, concentrate more where you see stain. You will probably need less than a pound. You can shut the filter off, or leave it on - the most important thing is to get a sequestering agent in the water, so that when the stain lifts off the surface of the pool and goes into solution, the sequesterant will hold it in suspension. After an ascorbic acid treatment you DO NOT shock your pool for 2 weeks.
1. Pour ascorbic acid down the sides of pool
2. Let water circulate for 1/2 hour
3. Pour in enough sequestering agent for the gal size of your pool (I would use a bottle of something like metal free, sequasol, or Jacks Magic.
4. Let the filter run 24/7
5. The next day check ph, add borax to take it back up to 7. to 7.2 (no higher)
6. After 48 hours start to raise chlorine slowly. It will be hard to get the water to hold chlorine because the chlorine will eat up the ascorbic acid that is in the water.
Your alkalinity is a little high, but the ascorbic acid may take it down. Make sure you check it also. If it is too low, you can add baking soda to bring your ph and alk up. Add small amounts and check at 2 hour intervals. With a cya of 50, you can take your chlorine up to 6, but not higher for 2 weeks. If you see stain start to reappear, then take your ph back down to 7 and add more sequesterant. Keep me informed, and feel free to ask any questions you may have.

[cmcq]

The stain treatment worked like a charm, but I have a follow up question.

I added the acid (1.5 lbs for a 22k pool) and sequestering agent on Sunday afternoon and let the filter run as described. I checked the ph last night (Monday) and it was steady at 7.2. I'm in Northern Virginia and it has been raining a couple of inches a day for a few few days so I'm not sure if the rain water helped raise the ph, but I did not have to add anything to raise it.

I checked the pool again this morning. The ph remained at 7.2 and the the chlorine was 0 (as expected), but the water is very cloudy and the pump pressure is very high (baseline is around 20 but pump is currently at 35). I couldn't backwash before work this a.m. and didn't want to run the pump all day with the pressure that high so I turned the pump off until I can backwash today after work. Is there anything about the stain treatment and sequestering agent that would affect the pressure in the filter that much? Also, with the cloudiness of the water, am I safe to re-start my SWG and to start raising the chorline level?