TXGlenn Posted May 9, 2011 Report Share Posted May 9, 2011 I've been in a struggle with metal stains for 6+ months now. Ascorbic acid takes it off, but when the chlorine starts to hold, the stains come back. My latest attempt to fix the problem was having a zinc anode installed which didn't help...metal stains came back when ascorbic acid was used up. The guy who installed my anode suggested the Cholox bleach (regular..unscented) that I'm using to bring up the chlorine level could have some additives that could be causing the metal stains. I had never heard of this. Can someone confirm or refute this? Thanks Quote Link to comment Share on other sites More sharing options...
chem geek Posted May 10, 2011 Report Share Posted May 10, 2011 Not true, and if anything the small amount of sodium polyacylate that is in Clorox Bleach may sequester some metals. See this link for what is in bleach. The reason the metal stains come back is that ascorbic acid will break up the metal oxides and reduce them (well, iron at least) into a more soluble form. However, you then need to remove that metal from the water or use a metal sequestrant to keep them in solution. Metal sequestrant will slowly break down from chlorine (HEDP based sequestrants break down more slowly) so you need to add more metal sequestrant to keep the metal in solution. If the sequestrant breaks down, then the metal ions can stain again since ANY chlorine will oxidize them (well, iron at least) and higher pH will cause them to stain again. The only thing even remotely true that the guy said is that using a hypochlorite source of chlorine makes it more likely for the pH to be higher if you don't manage it and keep the TA lower. So you are more likely to get stains again due to the pH -- not due to Clorox specifically. Also, a zinc anode would have absolutely nothing to do with staining unless the source of metal ions was corrosion of some metal in the pool and the zinc anode was electrically connected to the bonding wire and then buried in moist soil as a way to prevent further metal corrosion. However, a zinc anode will do nothing for preventing the staining of metal ions already in the water. Quote Link to comment Share on other sites More sharing options...
waterbear Posted May 10, 2011 Report Share Posted May 10, 2011 Are you using a phosphonate metal sequestrant (HEDP) like Jack's Magic or Proteam Metal Magic along with the ascorbic acid to keep the metals from redepositing as stain? If you are not you are only doing half the treatment. Also remember that sequsterant needs to be added weekly to monthly to keep the stains from coming back. Quote Link to comment Share on other sites More sharing options...
TXGlenn Posted May 10, 2011 Author Report Share Posted May 10, 2011 Are you using a phosphonate metal sequestrant (HEDP) like Jack's Magic or Proteam Metal Magic along with the ascorbic acid to keep the metals from redepositing as stain? If you are not you are only doing half the treatment. Also remember that sequsterant needs to be added weekly to monthly to keep the stains from coming back. Waterbear - I have been using sequestrants. Initially Metal Free and then Jacks Magic Purple stuff. The latest round I used 2 quarts of the Purple Stuff (pool is 19k gallons) initially. Per the instructions I needed to add 6-8 ounces per week as a maintenance dose. I figured I could get by the first week since I had just added 2 quarts but about 10 days after the initial does the stains returned. I've had the pool 3 years and the metals only became a problem after about a year and a half. I really wanted to find the source of the problem to avoid all this headache. Quote Link to comment Share on other sites More sharing options...
waterbear Posted May 10, 2011 Report Share Posted May 10, 2011 Are you using a phosphonate metal sequestrant (HEDP) like Jack's Magic or Proteam Metal Magic along with the ascorbic acid to keep the metals from redepositing as stain? If you are not you are only doing half the treatment. Also remember that sequsterant needs to be added weekly to monthly to keep the stains from coming back. Waterbear - I have been using sequestrants. Initially Metal Free and then Jacks Magic Purple stuff. The latest round I used 2 quarts of the Purple Stuff (pool is 19k gallons) initially. Per the instructions I needed to add 6-8 ounces per week as a maintenance dose. I figured I could get by the first week since I had just added 2 quarts but about 10 days after the initial does the stains returned. I've had the pool 3 years and the metals only became a problem after about a year and a half. I really wanted to find the source of the problem to avoid all this headache. Monitor your pH and do not let it climb ablve 7.8 If you see stains reappering then drop the pH to 7.0 and add another dose of sequestrant. How high is your TA? I assume the stains are brownish, which are iron, since these are the ones that respond best to ascorbic acid. If they are gray then it's manganses and it's coming from your fill water. Have you had your water tested to determine exactly what the metal your water is? That would be a first step in determining its source. Quote Link to comment Share on other sites More sharing options...
waterbear Posted May 10, 2011 Report Share Posted May 10, 2011 Are you using a phosphonate metal sequestrant (HEDP) like Jack's Magic or Proteam Metal Magic along with the ascorbic acid to keep the metals from redepositing as stain? If you are not you are only doing half the treatment. Also remember that sequsterant needs to be added weekly to monthly to keep the stains from coming back. Waterbear - I have been using sequestrants. Initially Metal Free and then Jacks Magic Purple stuff. The latest round I used 2 quarts of the Purple Stuff (pool is 19k gallons) initially. Per the instructions I needed to add 6-8 ounces per week as a maintenance dose. I figured I could get by the first week since I had just added 2 quarts but about 10 days after the initial does the stains returned. I've had the pool 3 years and the metals only became a problem after about a year and a half. I really wanted to find the source of the problem to avoid all this headache. Monitor your pH and do not let it climb ablve 7.8 If you see stains reappering then drop the pH to 7.0 and add another dose of sequestrant. How high is your TA? I assume the stains are brownish, which are iron, since these are the ones that respond best to ascorbic acid. If they are gray then it's manganses and it's coming from your fill water. Have you had your water tested to determine exactly what the metal your water is? That would be a first step in determining its source. Staining (and scaling if your calcium is high, remember that calcium is also a metal!) will occur when the pH spikes or when there is a sudden increase in oxidizer (which you shock the pool). If you are using liquid bleach for chlorinating then always add it to the skimmer. This way the localized high chlorine levels will be more likely to stain the filter medium than the pool surfaces. As far as Clorox's additive, sodium polyacylate, this is added to the bleach to sequester metals and to keep dirt from redepositing on clothes! It is also found in some pool clarifiers. It is not contributing to the staining. If anything it is helping to prevent it. If your staining is an ongoing problem I would suspect your water supply or the pipes it travels through. Another possibility is something rusting in the pool. How do all the exposed metal parts look? Are there any rusting screws, light rings, ladders, etc? Quote Link to comment Share on other sites More sharing options...
TXGlenn Posted May 10, 2011 Author Report Share Posted May 10, 2011 waterbear - My TA is around 100. The stains are brownish and I had my water tested for metals at Leslie's and they didn't see any using their test. I guess I should bite the bullet and get one of the Taylor 1264 kits but I know it's metals (based on the ascorbic acid working and the Jacks Magic Stain ID kit) so figured that was awaste of money. Although I can't remember now if it was iron or copper...I'll have to do the test again. I don't see any *exposed* metal pieces rusting. My light ring has turned gray-ish. Should I take it apart and check out the insides? Also, I have a heater which I have read can cause metal problems. It's only a couple years old. Is there any way to test it to see if that's the source of the metals? Thanks for your help! Quote Link to comment Share on other sites More sharing options...
waterbear Posted May 10, 2011 Report Share Posted May 10, 2011 waterbear - My TA is around 100. The stains are brownish and I had my water tested for metals at Leslie's and they didn't see any using their test. I guess I should bite the bullet and get one of the Taylor 1264 kits but I know it's metals (based on the ascorbic acid working and the Jacks Magic Stain ID kit) so figured that was awaste of money. Although I can't remember now if it was iron or copper...I'll have to do the test again. I don't see any *exposed* metal pieces rusting. My light ring has turned gray-ish. Should I take it apart and check out the insides? Also, I have a heater which I have read can cause metal problems. It's only a couple years old. Is there any way to test it to see if that's the source of the metals? Thanks for your help! Normally, brown stains that are easily removed by ascorbic acid are iron. Do you have iron staining in any of the sinks or toilets in your house or on any of your outdoor faucets? Iron can turn the water yellow when you shock (which can look green if you have a blue pool or liner) Manganese normally produces greyish stains and can turn the water pink to purple when you shock! (Pretty!) Its normal source is the water supply. Copper can turn the water (and your hair and nails) green and stains green, blue, black, or brown. Ascorbic acid normally is not very effective against it and acid washing is often needed in plaster pools. It can come from the water supply but the most common source is algaecides, ionizers, "mineral" systems, heat exchangers in pool heaters (particularly with trichlor is the main source of chlorination and pool water testing is lax so TA and pH crash) and pennies in the pool (kids will be kids!). Yeah, I know that pennies don't have that much copper in them but they can produce localized stains! Bottom line is this. If you a successfully getting rid of the stains and they a re reappearing quickly it is a water balance issue! Either you are bringing the FC up too fast (no more than .5 ppm a day!), shocking the pool during the first month, or allowing the pH to spike. (Dropping your TA to about 60-80 if your normal source of chlorine is bleach can help). Do you test your own water or rely on pool store testing? If you test yourself how often and with which kit? Quote Link to comment Share on other sites More sharing options...
TXGlenn Posted May 10, 2011 Author Report Share Posted May 10, 2011 Do you test your own water or rely on pool store testing? If you test yourself how often and with which kit? waterbear - I do my own testing with a Taylor kit. I am probably guilty of bringing the chlorine level up too fast as I grow impatient with it. I use more than enough ascorbic acid and thus it takes quite a while for the chlorine to start to hold....I will add a 182-oz jug of bleach every day (half in the morning half at night) for a week and have ZERO chlorine. Does the chlorine bring the metal out of suspension? If I am adding sequestrant every week, and I supposed to clean my filter cartridges every week as well??! Quote Link to comment Share on other sites More sharing options...
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