Yellow water after 1/2 water change and shock

bnairb · Postby **bnairb** » Mon 25 Jul, 2011 05:09

I drained about half the pool due to cya up to 90, refilled over the course of 1.5 days, now cya back down to 30. Water DOES come from a well. Everything was clear until I shocked it last night. I got up this morning and the pool water is yellow. Free chlorine level is about 9.5. My 1st thought was iron. The only metal test kits i have are aquachek's Total Iron and copper tests. They seem to test ok. I know coming from a well, the new water is bound to have metals/minerals in it. We use a sediment filter and water softener to help take the iron out. Knowing this, when I filled it I put in two quarts Orenda's metal and scale control http://www.orendatech.com/sc.html. So is it a different mineral/metal other than copper/iron causing this? What do I do now? I have guests coming in 4 days.

Postby **chem geek** » Mon 25 Jul, 2011 15:49

It's probably iron. If you lower the pH and the color fades, then it is very likely to be metal ions and a good metal sequestrant should help (the HEDP-based sequestrants are the best -- see Metals in the Water and Metal Stains for some recommendations).

bnairb · Postby **bnairb** » Tue 26 Jul, 2011 07:38

I stopped by the pool store on the way home yesterday. They said to take the chlorine down to zero, then use the metal chelator again, and to not chlorinate again for 48 hours. I'm trying to understand the whole metal removal process. I called the manufacturer of the product I used just after the refill and before the chlorination, and they said their product is a chlelator and just binds up the metals so they can't stick to surfaces, but that they won't actually be removed from the water, even through the filter. The product the pool person sold me yesterday is Natural Chemistry's Metalfree. I have not put it in yet, still lowering the chlorine. In reading about it, it says to use a filter aid, NOT polymer based like a clarifier, to help the particles be large enough to be trapped in the filter. They recommend their own product, Clear, which contains chitosan and no polymers.

So two questions before I waste my money, was the 1st manufacturer wrong in that the metal particles can't be "removed" (i'm not really keen on having bound metals floating around the pool), 2nd, is Natural Chemistry's approach with MetalFree and the chitosan based clarifier correct in actually removing the metal via the filter? I may not be able to get to the pool store for a few days to look for the HEDP based products you suggusted, so I'm wondering if you suggest I try the MetalFree, or wait until I can return to the store.

Postby **chem geek** » Tue 26 Jul, 2011 12:37

The standard procedure is to add a metal sequestrant which, as you point out, binds to the metal ions keeping them in solution so that they will not stain but does not physically remove them from the water. The HEDP-based metal sequestrants are more powerful and don't break down by chlorine as quickly. The Natural Chemistry Metal Free product is not as strong a sequestrant and will break down from chlorine faster, but it is "phosphate free" which is why they sell it.

The other approach is to intentionally precipitate the metal and then try and remove it using a clarifier. The problem is that such conditions can worsen staining -- the metal oxides that are formed can stain or they can form precipitate and it is not easy to control this. Some people take the approach of adding pH Up to their skimmer if the water is already saturated with calcium carbonate and this forms a cloudy calcium carbonate precipitate along with higher pH that can precipitate metals that then get caught in their filter. This approach is tricky to do successfully.

One other approach that is still too new to be certain it is consistently effective is to use CuLator™ in the skimmer. You would still do an ascorbic acid treatment to remove metal stains, but would then use the CuLator™ bag in the skimmer. If stains tend to return even when keeping the pH lower, then you'd need to use a metal sequestrant as well. The CuLator™ will physically remove metal ions from the water.

bnairb · Postby **bnairb** » Wed 27 Jul, 2011 11:26

I think I will give the CuLator a try. I took the chlorine down to zero and added the MetalFree. My water has pretty much cleared up so I will give another 24 hours before I add any chlorine. Thanks again. Very valuable information and much appreciated :thumbup:

bnairb · Postby **bnairb** » Thu 28 Jul, 2011 08:58

Chemgeek, thanks for all your help. Now I'm on to rebalancing the new water and hopefully can get your advice. I have guests coming tomorrow so I want to try to get this cleared up today. Hopefully you will have time to answer.

My pool is about 24000 gallons, vinyl lined, heat pump kept about 86 degrees. I still have not added chlorine since adding Metalfree. Today the pool has turned cloudy white. Not sure if that's related to no chlorine. I added Seaklear natural clarifier to see if that helps. So here are my current test results and I'm wondering if you could give me a quick target# on each to where you think would be ideal for my pool.

Chlorine - 0, still yet fearful to add any in fear of the pool turning yellow again after the water change.

Cyanuric acid - 30, I have not turned on the tablet feeder yet, would you turn it on and use the tabs, or would you leave it off and manually dose with liquid during the week to keep the cya from increasing again, or should I turn on the feeder and make sure I backwash an inch or two a week and monitor the cya?

PH - 7.3-7.4
T/A - 100-110
CH - 170, I do have calcium chloride flakes I can add, just not sure what's ideal having the heat pump copper in the mix.

I tested copper and iron again today after putting in the Metalfree 2 days ago. Seems relatively low to me, but not sure if this is still enough to cause any issues.

Copper - 0.2
Iron - 0.15

Thanks again for your time and advice, it is GREATLY appreciated

Postby **chem geek** » Fri 29 Jul, 2011 01:30

I would add acid to lower the pH more, say to 7.2 (but not below 7.0) and then slowly add chlorine to the pool. The cloudiness is probably algae starting to grow though it could be from the metal sequestrant if you added too much. Raise your FC level to 12 ppm to try and get ahead of the possible algae growth (assuming your CYA is at 30 ppm as you reported). If you lower the pH first, then the chlorine shouldn't cause a problem with the metals. Use chlorinating liquid or 6% unscented bleach as your source of chlorine.

Don't forget that adding acid or chlorine to the pool should be done slowly over a return flow with the pump running and then lightly brush the side and bottom of the pool to ensure thorough mixing. This is especially important for vinyl pools.

Dede free bird · Postby **Dede free bird** » Wed 24 Jul, 2013 22:32

chem geek wrote:It's probably iron. If you lower the pH and the color fades, then it is very likely to be metal ions and a good metal sequestrant should help (the HEDP-based sequestrants are the best -- see Metals in the Water and Metal Stains for some recommendations).

Use pool magnet. It worked magic on our yellow pool.