Ascorbic Acid Treatment

[Chrissymok]

This is our first season owning a pool (came with the house we bought). After opening and running the pool for a week we started to notice stains that, with the help of this forum, we determined to be from metals in the water. After lowering the ph and chlorine we used a metal out product and ascorbic acid to get rid of the stains. The ph is now back to about 7.2 but I am confused about how to go about raising the chlorine level back up since I have seen several posts about not shocking for 2 weeks. What is the best way to do this and avoid getting algae in the process? The pool store suggested a non chlorine shock? Just don't want to leave the chlorine level low for too long...any help is appreciated!

[aylad]

Hi, and welcome to the forum!! Just start adding the chlorine slowly, watching for signs of staining. If you see them, add more sequestrant. If not, just slowly raise it to whatever your target Cl is, based on your CYA level (see the Best Guess Chart stickied at the top of the Chlorine forum). It may take a good bit of chlorine to get back up there, my understanding is that both the sequestrant and the acid eat up a good bit of it. Most of us on this forum use plain, generic, unscented bleach for chlorine--12.5% liquid chlorine is not available in my state, but others on the forum prefer to go that route...

Janet

[Chrissymok]

I added a small amount of chlorine last night and by this afternoon I already see the staining returning! I am so frustrated by this. I guess that means I need to add more sequestrant, but my question is how often will I need to do this? I am on city water and don't have a heater...I can't figure out how metals could have gotten in the water in the first place. Any help would be greatly appreciated.

[Watermom]

You may have to add sequestrant each time you add water. Marie, our metals expert, can better advise you. She'll be popping on here at some point and I'm sure will take a look at this thread. Hang in there ........

[mbar]

If you give us a full set of numbers we can help you. Sometimes the water needs to be balanced before the stains will stay away.

[Chrissymok]

Here are the numbers that we got from having the water tested:
Free Available Chlorine .2
Total Chlorine .2
Total Alkalinity 103
ph level 7.2
calcium hardness 23
Cyanuric Acid 99
copper .4

we were told (by pool store person) that we needed to drain 1/3 of pool to get the cya level down and add calcium. Then add more stain out. Does this sound right? Of course, everytime we talk to someone else, there are more chemicals and lots more $!!! Thanks for all of your help!

Pool Info: inground 16,000 gallons, sand filter

[mbar]

It does sound like you need to get your cya down. This is what I would do first:

Drain and refill about a third of the water.
Add calcium to get it up to 250 - 300
Keep your ph at 7.2
add bleach to get your chlorine up to the best guess chart of chlorine and cya that is in the sticky in the chlorine forum.
Add the bleach slowly - one jug at a time
If you see stain start to come back, then add more sequestering agent.
If the stain persists more than a day after the sequestering agent, and your ph is still no higher than 7.4 add more ascorbic acid (or citric acid).
Keep the pump running 24/7.

I think after doing this the water should be fine - whenever you get high chlorine along with high ph and there are metals in the water and not enough sequestering agent the metals will fall out and stain the surface of the pool. If you have metals it is always a good idea to keep the ph around 7.2. I always use the sequestering agent first before any stain treatment because it will generally lift any new stains. Let me know if you have any other questions.:)

[Chrissymok]

Thank you so much for all of your advice...the pool stores have no idea how to handle this! My other question is about the best guess table...I am not sure how I should be reading it. Any help with this is appreciated greatly! Thanks!

[Watermom]

The best guess table is to help you determine how much chlorine you need to maintain in your pool all the time, and how high to shock the pool when that is needed. It is based on the cya level in your water. For example, if your cya level is 40ppm, then you must keep your chlorine between 3-6 all the time and if you need to shock, you will need to take the chlorine level up to 15.

Does that answer your question about the table? If not, repost with a more specific question and we'll try again.

[Chrissymok]

Yes, that answers my question about how to read the chart. Right now my cya is high and I have to get it down, but not sure what number I am suppossed to be getting it down to.

[Watermom]

I like around 40. What is it your level currently?

[Chrissymok]

currently it is 99...that's why we need to get it down

[mbar]

Anywhere between 30 - 50ppms

[Chrissymok]

After draining 1/3 of the pool and refilling (twice!) we still only got the cya level down to 76. With the FC down to 0 we used a stain out product and then a metal out product. The pool looked great...until we added chlorine back in...now all surfaces are stained again. This is the 2nd time we have done this whole process and while the copper has gone down from .4 to .1 we still can't seem to get it out. The stain out and metal out are pretty expensive and we don't want to keep having to use them. Our public water has no copper in it...we think it must have come from algecide that the pool openers used. How can we get better results that will last? Can we ever totally remove the copper...or will we eventually have to drain the entire pool? We feel like we are going to be battling this forever and we don't want to keep throwing $90+ away everytime we try to treat the problem. Any advice would be appreciated, thanks!!!

-16,000 gallon inground pool, with vinyl liner & sand filter

[pilot-werx]

I was in the same boat as you and have tried just about everything... My CYA is higher than yours (100) and here is what I have done with the best results. (Dumping water was not an option)

If your water is clear, stop feeding chlorine and let the levels come down to 1 ppm or so. For your amount of water, get about 2 lbs of ascorbic acid and two bottles of ProTeam Metal Magic. When the chlorine drops, bring the pH up to around 7.6-7.8. With the pH correct, add the ascorbic acid it the skimmer. Let the acid circulate for a couple of hours or until the stains have disappeared. When the stains are gone, add two bottles of Metal Magic. Wait 24 hours and then start to bring the chlorine up. Do not add any shock or liquid chlorine. If you have a feeder, put it on its lowest setting. If you put tabs in the skimmer, just keep an eye on your chlorine levels. You do not want to go higher than 2-3 ppm. If you have high metals, every week, you will need to add metal magic.

I have been fighting this all summer and so far this has been the best. The ascorbic is expensive but the Metal Magic is $17 at my local store. I feel somewhat stupid because I am a water engineer and this has been the hardest thing to deal with.

Give it a try and let me know how it goes.

Regards,
Chris

[mbar]

Hi Chris, you have it about right. The most important thing is to never let the chlorine get too low or you risk an algae breakout then you have to shock.

Chrissymok, I feel your pain. This is what I would try before doing the whole ascorbic treatment again. Lower the ph to 7.0-7.2, add more sequestering agent proteams metal magic is my choice also. Keep your chlorine at the lower end of the "best guess chart" for a while. The new stains should disappear without the ascorbic acid. If the stains are still there after a day or so, then add a small amount of ascorbic at a time, letting the water circulate between additions until the stain is gone. Add more sequestering agent if you see stains start to appear when your chlorine level is back to normal. Remember high chlorine along with high ph is what makes the metals fall out of solution. As for where your metals are coming from, it is hard to say. If it is from something you added, it should go away with time as your water is replaced.