Metal Cure?

Stains on the pool surfaces, pool equipment
or on the swimmers, or off-color swimming pool
water. Discolored but clear pool water.
captjohn
Pool Newbie
Pool Newbie
Posts: 5
Joined: Thu 04 Jun, 2009 12:27
My Pool: Fiberglass, Indoor Glass Room, free form, jetted 15,000 gal, 1 1/2 HP Pentair pump, Triton 100 Sand filter, Chlorine system, Heat Siphon Heat Pump, auto chlorinator, waterfall and an 8' slide.
Location: Mississippi Coast

Metal Cure?

Postby captjohn » Tue 10 Nov, 2009 10:53

On 10-30:
My pool is indoors and was cloudy/white 2 days ago w/low FC for 1 day. It's been beautiful for the last 3 months. I shocked w/recommended 12 to 16ppm FC w/6% unscented bleach for a cya of 35, ph was 7.2. Water turned green and very cloudy. I kept chlorine level at 16ppm all day and night. Usually pool would clear up by now. Yesterday I upped the FC to the 24ppm for mustard algae per The Pool Calculator but overshot and at 30ppm. Ph at 7.0 and aireating w/jets to bring that up. The water never turned white as I expected for dead algae. Expected to see clear water this morning but still green tint and fairly clear. Backwashed but very little came out. I added Super blue (clarifier) yesterday w/no results.
It can't be algae so must be metal. Copper was suggested but I can't find anyone to test for it. I was leaving town for a few days so I added 3 qts. of Regal Metal Out (twice the initial dose) and ran pump for 24hrs. No results and nothing came out of filter backwash.
Back home and no results now after 5 days. The water is still fairly clear w/green tint. The FC may have been too high for the sequesterant but I was out of time.
I'm on well water and use bleach to chlorinate and muratic acid to lower PH/TA. I also use citric acid for staining.
I installed a new heat pump a week before this happened. Seems suspicious but the exchanger is titanium.
Test results from 11-10 (very similar results on 10-30) w/TF-100 kit

fc-8.0
cc-.5
tc-8.5
ph-7.4
ta-180 (high I know)
ch-300 (ditto)
cya- 30
water temp- 80

Lot's of info here (sorry) but any Ideas?


chem geek
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Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Metal Cure?

Postby chem geek » Tue 10 Nov, 2009 11:19

Does your pool have blue-colored walls/floor? If so, then it could be iron (from the well water) where the yellow from iron plus blue from the walls can make the water look green. However, unless there is a whole lot of iron, I wouldn't expect to see it at the low pH of 7.0 -- shocking with a lot of chlorine should have temporarily raised the pH as well where the combination of oxidation from high chlorine levels and higher pH could have precipitated iron oxides and carbonates.

You could try lowering or keeping the pH low at 7.0 and adding a metal sequestrant. You can aerate the water and then add more acid when the pH rises as this combination of acid addition with aeration will lower the TA.

You might consider using a metals filter for your fill water, if possible.

[EDIT] I notice you say you tried the sequestrant already in this thread . [END-EDIT]
captjohn
Pool Newbie
Pool Newbie
Posts: 5
Joined: Thu 04 Jun, 2009 12:27
My Pool: Fiberglass, Indoor Glass Room, free form, jetted 15,000 gal, 1 1/2 HP Pentair pump, Triton 100 Sand filter, Chlorine system, Heat Siphon Heat Pump, auto chlorinator, waterfall and an 8' slide.
Location: Mississippi Coast

Metal Cure?

Postby captjohn » Tue 10 Nov, 2009 11:37

No, the pool is white. The ph went up when I shocked but I added Muratic acid to bring it back down.
Some one on another forum made this statement and I'll ask for your input:

"The green colour could come from manganese which is commonly found with iron (used to make green bottles so may give you a clue) in some well water.

It could also come from copper, copper can deposit different colours depending on what compound of copper it is. Green would be produced if you were using hydrochloric acid (Muratic acid) as a PH reducer. If you add concentrated hydrochloric acid to a solution containing hexaaquacopper(II) ions, the six water molecules are replaced by four chloride ions.

You may find the colour of the tetrachlorocuprate(II) ion described as olive-green or yellow. If you add water to the green solution, it returns to the blue colour.
So it is a reversible reaction."

If this is true, a partial water change may help?
I was using a sequestrant regularly but was still staining pool brown. I stopped that and just used citric acid for stain removal. Maybe I shouldn't have stopped. It may have worked better than I thought!
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Metal Cure?

Postby chem geek » Wed 11 Nov, 2009 00:45

Metal sequestrants are not permanent. They slowly breakdown from chlorine so you need to add more over time or else they release metals back into the water when the break down and staining or coloration can occur again. Water dilution with water free of metals is the only way to completely remove the metals of the water so long-term such water replacement is the thing to do (unless you are on well water and have no way to get water trucked in at reasonable cost).
HydrogenHydroxide

Metal Cure?

Postby HydrogenHydroxide » Thu 12 Nov, 2009 01:38

The green is copper from your old heater.

Any pool place should be able to test for metals. In addition, any water conditioner place should be able to test for metals. Ask the water conditioner places about systems for removing metals.

Have the water tested for iron, copper and manganese.

Have you added any calcium hypochlorite or pH up (sodium carbonate) recently?

Have you ever use trichlor tabs?

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