copper algaecide

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purple_duckk

purple_duckk

0
Mar 21, 2009
34
Detroit
So before I found this board I was trying to open a pool that was sitting for two-three years before I bought the house and I enlisted the help of my bio-chemist brother to see what I could use to eliminate the green water I had. He suggested copper sulfate as it is pretty easy to get and destroys algae pretty well and sticks around for a long time. Long story short he got me a couple of pounds of pure copper sulfate crystals and now I'm pretty sure my water is blue because of the copper. I have been dilligently vaccuming and brushing the sediment off the bottom of the pool for 2 or 3 weeks now and if I let the pool sit for a day or two the water clears up a bit, but I can't see the bottom of the deep end. Not even close. I have held my chloring to shock levels for about 2 weeks now so I assume the opaqueness of the water is due to the copper, so is there a way to clear that out without draining and refilling it?

TA - 100
FC - 22
TC - 21.5
CH - 350
CYA - 40
 
You can try a metal sequesterant. HEDP based.

Usually when it's a metals issue though, the water is not opaque but transparent with an "off" color.

Copper is never advised in a pool because in certain conditions it can cause staining, that is usually permanent. Also it turns hair green.

Until the water is replaced, consider it in the water. You should have your level tested.

What are you testing with? Is your FC holding overnight?

FC + CC = TC, so your total chlorine can't be less than your FC. Typo?
 
Here are some pics. remember I used several pounds of pure Copper Sulfate and some sort of disappating reagent that would allow the algae to absorb the copper faster.(my brother specializes in the chemicals used to keep large fields of water usable , so he has this stuff on hand) Enought that it turned the pool from deep emerald green to this unnatural blue color in the span of about 6 hours. It has become much much clearer as I have been vaccuming up the junk on the bottom and running the filter 24/7 and backwashing hundreds of gallons out of the pool and refilling when it gets too low. And yes, I flipped my FC and TC levels. I have been able to hold my FC overnight quite easily and I have been able to maintain the high level of FC for the past 2-3 weeks by adding only small amounts of liquid chlorine so I'd say there is nothing living in there.
 

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It can take a long time for a sand filter to clear up dead algae.

I don't think the clarity issue is from the copper. (The color is off a bit.) Get the copper level tested.

It's nice that he's helping you but some of these "fixes" aren't practial for swimming pool use, I'd avoid copper in the future.

I'd just make sure the sand is not channelled, that you aren't backwashing too much, try a little DE in the sand filter (instructions in Pool School). Have some POP.

If you are certain the FC held. You used an FAS-DPD test to determine this?
 
Yeah, after I found this forum I wouldn't have used the Copper, but we did this a couple of months ago. In the future I'll just shock the bejezus out of the pool if it ever gets that bad again. I hadn't had the filter running because I had to lower the level so I could repair some marcite and tile damage and it had been sitting for years before I bought the house so it was about as gross as you can imagine and I was looking for a fix.

As for the sand filter I have washed out the sand 3 times since I started the project and now I am backwashing about once every 3 days if I just let the pool sit and pretty much immediatly after brushing the whole pool. When I dive to the bottim of the deep end there is some granular sediment that could be from my marcite repair that I have been scooping out with my leaf rake and vacing up as much as I can when I can see it.

How would you suggest I get the water tested for copper? Would the average pool thieves at the store be able to test for that?

I'll give using some DE in the filter a shot. I assume the DE would come out when I backwash though right?
 
I have not added any sequesterant yet. I wanted to get the advice of the experts here before I did anything else. Is there one in particular you would recommend, and what are the effects of use i.e. sediment dropping out or another compound being created?
 
1ppm or above is a problem, staining could be an issue. .3-.6 is usually considered"algae control" typical level, any level will likely turn hair green.

Sequesterants will keep it "in solution", so it won't stain the pool, but they need to be used on a routine maintenance basis to be effective. It can be expensive. If the copper starts to stain the pool surface, the water won't test postive for it. Once sequesterants are used, and the copper is back in solution water that tested negative for copper before might show postive on subsequent tests...if that makes sense.

I can't remember where you are located, but if you winterize the levels should be lowered thru water replacement. Two years ago (pre TFP I used to have high copper levels but now mine is nil.

Basically you can't "take it out" - it is in your pool until replaced with fresh water, the sequesterant just prevents staining.
 

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Yikes, I was kind of afraid of that. Looks like I'll probably drain a large amount of water out. 2 pounds of Copper Sulfate for 24,000 gallons at about 8 pounds per gallon would be about .001% Without knowing the molar weight I don't think I can figure out the ppm, but I'm going to guess its pretty high.
 
2 pounds of copper sulfate in 24,000 gallons is (1,000,000 ppm / weight-ratio) * (2 pounds CuSO4) * (63.546 g/mole Cu) / (159.61 g/mole CuSO4) / ( (24,000 gallons) * (8.33 pounds / gallon) ) = 4.0 ppm copper. [EDIT] This assumes that anhydrous copper sulfate was used. If it was copper sulfate pentahydrate (249.68 g/mole), then the result is 2.6 ppm copper which is still high. [END-EDIT]
 
2 pounds of copper sulfate in 24,000 gallons is (1,000,000 ppm / weight-ratio) * (2 pounds CuSO4) * (63.546 g/mole Cu) / (159.61 g/mole CuSO4) / ( (24,000 gallons) * (8.33 pounds / gallon) ) = 4.0 ppm copper.
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Shoot, I was gonna' post that and Richard beat me to it :shock: :shock: :shock:

Richard, you are such a valuable contributor to this forum, your pay should be doubled. :-D

Seriously, all of us are very appreciative of the special skills you have. We benefit from your expertise.
 
So the pool was drained pretty quickly, now comes the long long long process of refilling. I wonder if I can talk the water co into installing a 3" line at the house. On the plus side draining the pool forced me to make a perm plumbed backwash line out to the driveway instead of just into the side yard.
 
I'm sorry if I don't understand all the calculation. So maybe you can help me with my copper sulfate amount...

I have an 18 foot pool which equates to 28000 liters (yes liters since I live in Canada) ;)

I read that you need 1g per cubic meter of copper sulfate to maintain your pool free of alguee. so Basically I need 28 grams of copper for my pool... Is this true?

A friend told me I need to be at 0.40 ppm but I don't understand how he could measure the copper sulfate to come to this amount. Can someone help me please?

Thanks :)))
 
Re: algaecide copper sulphate pentahydrate granules

cmlegend: The instructions I have are 1 teaspoon per 6000 gals every 2 weeks for maintenance.
for visible algae or opening, use 2 teaspoons per 6000 gals.
I mix in a bucket until disolved then distribute into pool.

There are lots of metric conversion tables on the web ( google metric convert).

Works great for me!
 
cmlegend, Welcome to TFP! :wave:

1 cubic meter is 1000 liters so 1 gram in 1000 liters is 1000 milligrams in 1000 liters or 1 mg/L (ppm). That's copper sulfate pentahydrate concentration. In copper units it's 1 * (63.546 g/mole Cu) / (159.61 g/mole CuSO4) = 0.4 mg/L (ppm) copper. So 28,000 liters would need 28 grams of copper sulfate pentahydrate to get to 0.4 ppm.

HOWEVER, you don't need to use copper to prevent algae growth and copper can stain pool surfaces and turn blond hair greenish. All you need is chlorine alone, at a level appropriate to the Cyanuric Acid (CYA) level. Read the Pool School to learn more about how to maintain our pool.
 

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