Yellow Staining, Acorbic Acid Works Well, BUT.....

[Watermom]

Hi, Chris and welcome to the forum! I'm going to alert Marie to take a look at this thread for you.

[mbar]

Hi Chris, welcome to the forum You always need to follow ascorbic acid treatment with a metal out (sequestering agent). Any good metal sequestering agent will do - good ones usually run about $20 a bottle. I have used Jack's Magic, Sequasol, Metal Magic, and a few others that all seem to work the same. I put the metal out in as soon as all the stain is lifted (about a half hour later). The reason you need a sequestering agent is because the ascorbic acid lifts the stain off the surface of the pool, putting the metals back into solution. The sequestering agent then holds the metals in solution keeping them from redepositing onto the surface of the pool. Try to keep your ph on the low side for a while. High chlorine along with high ph is what causes metal to fall out of solution. If the metals stains start to come back when raising the chlorine levels, take the ph back down to 7.2 , and add more sequestering agent - this will usually remove any light stains that are starting. Please give me a set of your pool chemistry numbers (ch, ph, alk, calcium, and cya). If you have any questions feel free to ask

[pilot-werx]

Thank you for the reply.

My numbers as of a few moments ago are:

chlorine : 0.5ppm
ph: 7.6
alkalinity: 90
calcium: 250
cya: 50

I am a little concerned with the chlorine that low as with the water heated to 82, it is only a matter of time before algae forms... However, right now the water is crystal crystal clear...

What are your thoughts on oxalic acid instead of ascorbic? The reason I ask is that oxalic is half the cost of ascorbic around here. I think there is a dealer close by that has Pro Teams Metal Magic. I will pick some up and try that.

How do my water balance numbers look?

Thank you for your help.

Chris

[chem geek]

People have used citric acid, which is also less expensive, and it seems to work but just takes somewhat longer. I know that oxalic acid is also a reducing agent so in theory it should work, but I don't know how well.

As for preventing algae, one usually adds PolyQuat 60 to the water when doing an ascorbic acid (or citric or oxalic acid) treatment in order to prevent algae from growing during the treatment.

[mbar]

I second what chemgeek said. I have used citric acid and it works well. You just have to use more of it. Here is a link to ascorbic that isn't too expensive:

http://www.msm-msm.com/store/agora.cgi


Here is one for citric acid:

http://www.chemistrystore.com/search...to+Search2.y=0

The rest of your numbers look good. I always use the polyquat 60 when doing the ascorbic acid - especially if the water is warm, you also want to keeep your ph levels at 7.0 to 7.4 while slowly raising the chlorine levels back up. Let us know how you do, and if you have any other questions

[staclear]

How well the Citric Acid works on Gunite walls ? How many pounds I need for 23000 Gallons of water to remove brownish yellow stain due to winter elements.

[mbar]

Citric acid will work, however you will need more citric acid than ascorbic acid. I would start with about 5 lbs of citric acid. Pour 1/2 in and put your filter on circulate. Add enough sequestering agent (metal out) per directions on the bottle. You can add a little more of it later if you need to. Allow the pump to circulate for a couple of hours. If the there is still staining add more citric acid. Once all of the stain is lifted you can put the pool back on filter. Make sure you have the sequestering agent in the water or when you start to balance the water you will just get the stains back. After the stain is gone and you rebalance the water, if the stain returns then you bring your ph back down to 7.2 and add more sequestering agent. Feel free to ask any other questions you have

[waterbear]

People have used citric acid, which is also less expensive, and it seems to work but just takes somewhat longer. I know that oxalic acid is also a reducing agent so in theory it should work, but I don't know how well.

FWIW, oxalic acid is what is used in United Chemical's Pool Stain Treat and Pool Stain Treat spotting bags. I can't really tell a difference in how fast it works compared to Ascorbic acid but Citric does seem to be a bit slower. However oxalic acid is the most toxic of the three with ascorbic acid being the least toxic.

[mbar]

Make sure as you raise your chlorine levels you add more sequestering agent if you see stains coming back. Add the chlorine slowly - that's why I like to add bleach. You can add it in small amounts till you get it where you need it to be.