possible metal stains

[kostia]

Hi,
It seems that I have some metal staining (light brown spots in a bunch of places) more in the corners. Metal was high in the water so I used natural chemistry metal free to lower it.
Hopefully that worked, but stains remain. So now what I understand I need to do is add either ascorbic or citric acid.
I found this citric acid at amazon .. I think this should work? http://www.amazon.com/Spicy-World-C...F8&psc=1&smid=ATVPDKIKX0DER&tag=r601000010-20
After treating the water with citric acid, I plan to add more metal free to neutralize whatever is left in the water.
Is this a good plan?

 

[JasonLion]

Metal Free is not one of the sequestrants we recommend. Sequestrants based on HEDP, phosphonic acid, or phosphonic acid derivatives are far more effective. ProTeam's Metal Magic and Jack's Magic The Pink Stuff (regular), The Blue Stuff (fresh plaster), and The Purple Stuff (salt) are some of the top sequestrants. You can also find many other brands with similar active ingredients, some of which are noticeably less expensive.

Sequestrant almost never removes metals from the pool, it simply holds them in solution so they can not form stains. Unfortunately, the sequestrant breaks down slowly over time, so it needs to be constantly replenished. Some brands last far longer than others.

The citric acid you found is fine.

We have instructions for removing stains here. If you use citric acid, you need to use roughly twice as much as if you are using ascorbic acid. Even so citric acid is usually less expensive.

 

[kostia]

I have pebble tec like surface (glass with plaster mix) is any of the sequestrants better than other for this or any one of the recommended would work? Is there anything that can be done to eliminate metal? i have not had these issues last year although I filled the pull in the Spring of last year.

 

[ftbn]

Concerning the Ascorbic treatment:

How long (approx) does it take for the water to "hold" bleach levels? I have a smaller 7K AG 18ft round and have gone through 2 gallons of 8.25% within the past 20 hours.. (I've been adding 1/4 gallon at a time with constant testing)...

Also, while I'm here: Anyone know if the Ascorbic treatment eats CYA ??? the past 2 months, my CYA has been at (a very high) 65... (this includes a test I did 5 days ago).. When I tested 24 hours after the Asc. treatment, CYA was -ZERO- ((( Other chemicals added within the past 5 days: PolyQuat 60%// and Nat Chem Metal Free..

(( To answer the obvious question concerning the bleach "Holding": I lost 4 PPM FC overnite... Water is crystal/ PH: 7.2-------Alk: 90

Thanks Folks !!

 

[chem geek]

If you didn't use Polyquat algaecide during the ascorbic acid treatment, then when the chlorine went to zero bacteria can grow and consume the CYA. If they converted it to ammonia, you will have a huge chlorine demand up to 160 ppm FC or so whereas if they converted it to nitrogen gas there will be no extra chlorine demand.

 

[ftbn]

Chem-Man:::: Much appreciated !!! in fact, I did use poly during the Ascorbic Treatment>>>>>> HOWEVER, I did NOT use it a week ago when I dropped levels for the Nat Chem Metal Free "treatment".... ( This has always been my cure all for metals, but this year nothing has been working....)!!
Stabilizer time I guess....

While I "have you here" ::: Is there an easier/ more fool-proof way to do the CYA test on the 2006 ??? I always wonder if that "dot" that's suppose to disappear, is not actually my reflection looking inside that pea-size hole in the comparator ??? : >

 

[chem geek]

Stand with your back to the sun and hold the tube in front of you and look straight down into it. That's the ideal strong indirect lighting condition you want for the test. If you are unsure, pour the solution back from the tube into the bottle and do it again as often as you like. See this link for photos of how the black dot disappears. If you aren't sure it's there, then count that as not being there. The endpoint of the test is when it goes from being able to see it to at least not being sure -- if you keep going and it doesn't seem to change significantly then you already found the right level.

 

[kostia]

If I understand the process correctly, citric acid will reduce chlorine levels or chlorin levels must be reduced regardless for less citric acid to be effective. However it is not recommended to shock the pool after treatment. What is the recommended way to increase chlorine levels after treatment?

 

[chem geek]

For any metal stain treatment involving a reducing agent, be it ascorbic acid, citric acid or oxalic acid, these will react with chlorine so one wants the chlorine level to be initially on the low side so as to minimize the expense of the reducing agent that will be wasted just reacting with the chlorine. The excess reducing agent then works on the stain to remove it and a metal sequestrant then binds to the metal ions to keep them in the water. When chlorine is then added, it reacts with the leftover reducing agent (that which did not react with the metal stain).

One doesn't shock after treatment because shocking (with hypochlorite) raises the pH and that can cause stains to reappear if enough metal sequestrant hasn't been used to hold metal ions. Also, chlorine oxidizes metal sequestrants so shocking accelerates that and will release the metal ions which can then stain again. So one should slowly raise the chlorine level and watch for re-staining. If some occurs, add more metal sequestrant.

Even after one gets to the normal chlorine level, one still needs to add metal sequestrant weekly to make up for that which is broken down by chlorine. One of the reasons we recommend HEDP metal sequestrant is that it is more resistant to breakdown from chlorine (especially compared to EDTA).