copper sulphate as Swimming Pool Algae Remedy?

A. Hi Thomas. There are some very insightful answers on this page; I personally really like the ones from Garry Sunderland and Randall Gatlin. But you'll have to do some arithmetic to scale up from their suggestions.

Luck & Regards,

A. I occasionally use copper sulphate(we use "f" instead of "ph" in the states, eh?) in my pool. Municipalities have been using it for years to control algae growth in surface drinking water supplies. copper sulphate is not a substitute for chlorine or other purifying media. It is, essentially, a metallic poison that in small concentrations inhibits algae growth. I use it in 1-2 mg/liter (as copper sulphate) concentrations. You should have access to a source to analyze trace copper should you need to add more. Like I said, copper sulphate is poisonous, so use it at your own risk.

A. Hi Tracie.
The reason sellers do not tell you about copper sulphate is as clear as the pools that have copper sulphate in them (including mine): it would crush their income.
A large % of their income comes through repeat selling chlorine to customers.
I added two cupfuls to my pool two years ago and it has been clean ever since - Crystal clear in winter.

A. One part per million of copper in drinking water is quite safe, and 0.5 parts per million is enough to control green algae in swimming pools. Most copper sulphate contains around 20-25% copper, so a 50,000 liter pool would require 100 - 120 grams copper sulphate if the pool is green I would give a once off double dose. Test kits are available to test the concentration of copper in the water. A word of caution, copper used in conjunction with too much chlorine will eventually cause black stains on marble plaster, although these can easily be removed by "acid washing" the pool. One cup of calcium hypochlorite per week will be enough to keep the water sanitised. As always maintain a pH of 7.2 - 7.6

A. Another name for calcium hypochlorite is probably 'chlorine tablets'. So, no, these don't remove the black stain, excessive use of them can cause the stain.

A. Calcium Hypochlorite is also known as unstabilised chlorine , i.e., it is not combined with cyanuric acid. It comes in granular or tablet form. Stabilised chlorine, e.g.(Trichlorisocyanuricacid) is usually in tablet form in those floating chlorinators . Both are chlorine and will stain marble plaster black when used with copper.

Copper sulphate, whilst being an excellent algaecide will not sanitise (disinfect) your pool water; that's where the chlorine comes in, or you could use hydrogen peroxide ⇦ this on eBay or Amazon [affil links] it will sanitise the water and won't stain the pool,it has the added benefit of being harmless to the ozone layer (it breaks down into hydrogen and oxygen). Draining the pool and washing down with a weak hydrochloric acid solution will remove the stains. Ask the guys at the pool shop how to do it, so you don't damage your plaster.

A. A chelating agent will remove the copper from the water (ask at the pool shop) As for the hair, a little vinegar ⇦in bulk on eBay or Amazon [affil links] in the final rinse after washing should remove the green tint.

A. I have been using copper sulphate in my above-ground (11,000) gals. At a rate of 4 TEASPOONS of the Granular dissolved in 4 gals of water then poured evenly around entire perimeter of the pool. I do this once a month. Additionally, I add one lb. of granular Shock about once every 6 to 10 days, depending on traffic and rain. I have been doing this for 4 years and have the bluest cleanest pool around. The amounts I use were prescribed to me by an engineer who works for a chemical company that sells to municipalities all over the SE U.S.
Naturally you are not going to get any information about this from your pool supply companies. I pay $25.00 for 5 lbs. of Copper sulphate, which is about a 6 to 8 year supply.

A. Hi Sheryl. To my knowledge, there is no particular difference ... but we'll see if someone calls me out as wrong.

Assuming they don't, I'd say you're less likely to stumble on something and hit your head and drown in the daytime or encounter a skunk or porcupine or other nocturnal animal :-)

Regards,

A. During the past twenty years or so I have used an electronic copper ion generator .... two electrodes into my filter unit ... which operates with the filter timing sequence. Before that I used Copper Sulphate. Very inexpensive and effective in my 80,000 liter pool. Be very careful when you put in any pool chemicals. READ the labels and understand what they mean. We have pool companies that will sell you acid at 4x the price by calling it 'Pool Sparkle'. Everything is poisonous ... in excess (there are even toxic relationships). Do your homework. Ozone or UV are sanitizing options to replace chlorine but algae control is not part of that protocol ... except that chlorine will kill or bleach algae. I have found that a neutral pH is the first parameter to control.

20 Mule Team Borax

on eBay or

Amazon

(affil links)

A. I have been using copper sulphate for many years now at the .5 PPM ratio, and of course chlorine, as a sanitizing agent. There is a trick to using this which I have yet to see posted and that is to also add 1 lb. of powdered Borax /10,000 gallons of pool water. Borax ⇨
removes oxygen from the water and ties it up as H2O2 (hydrogen peroxide ) in the pool water, this is degraded daily by sunlight, it is harmless to you at this dilution, it will prevent algae ever becoming established when combined with chlorine and copper sulphate, it will also kill out established black algae in the pool.

A. Hello guys, let me share my experiences ... I have a 18000 gallon in-ground liner pool. It is equipped with a sand filter and a post filtration cartridge filter plus a homemade copper ionizer. I actually add copper sulphate to maintain .300 ppm limit. Add one pound and check the copper concentration with a copper concentration kit. Have not had any problems ever !
When I see spots of brown algae, I drop shock granules where the algae spot is, using a PVC tube, and it is gone in minutes !

A. A few years back there were claims all over the internet about borax being the ultimate pool treatment. I tried it.

As best I could tell, even in fairly large quantities it did nothing at all.

A tiny bit of copper, 1 ppm or so, is the trick to control algae. I happen to use copper napthenate because I have some, but copper sulphate is fine.

You can buy a copper test kit for a few dollars ⇨
or you can add just a tiny bit (as in the above responses) a few times each season.

Of course you must still control pH at 7.2 - 7.4 or thereabouts, and you need chlorine to be certain there are no pathogens or other harmful microbes.

A. Believe it or not, in the European Union Borax and Boric Acid are SVHC's.

? Hi Eileen. Sorry but I don't even quite know what that means. I would think that everyone is "allergic" to copper sulphate -- it's a poison. But many ponds and medium sized lakes are dosed with copper sulphate. What (if anything) does her doctor or dermatologist say about her condition and this situation?

Regards,

Hi Bobby. Randall's posting was from over 2 years ago, so we don't know if he'll reply -- we'll see. But we can't discuss what ingredients particular suppliers use in their trade-secret products in this public forum (beyond what is revealed on the SDS) -- that comes too close to trying to crowd-source industrial espionage :-)

Regards,

A. Many metals corrode. Only iron alloys, i.e., steel, rust.

Your pool heater "rusted out"? That makes no sense. Most pools use chlorine which, by itself will cause rapid rusting of plain steel. Copper may accelerate rusting of steel.

The bottom line is, in my opinion, steel is completely inappropriate for heat exchangers which have contact with swimming pool water.

If you were sold a steel heat exchanger for swimming pool use, you have a valid complaint with the manufacturer.

If it is a gas fired unit, the heat exchanger parts which contact pool water should be copper or a chloride resistant stainless steel alloy like 316. I used a copper/solar heater for many years with zero leaks.

If a low pressure solar heater, then plastics like PVC or polypropylene can be also used.

Steel? No. No way.

But, if you still want to get the copper out, dump and replace the water.

A. Algae needs 5 things to live: water, sunlight, carbon dioxide, nitrates, and phosphates. Take away any one, and it will die. Phosphate remover, though expensive, is very effective. BTW, phosphates come primarily from pee in the pool water. Don't pee in the pool, and algae control becomes much easier.

I am a pool pro. I used to use copper sulphate pentahydrate, but discontinued it. I was getting green hair complaints from my customers. You also risk having an unsightly purple precipitate from the copper with pH changes.

A. Hi Kathy. I think what's best is good mixing. Pouring it around the edge, maybe stirring a bit with a paddle, while the filter is on is probably fine. But it would be better to pour it into a watering can and dilute it first. Usually, the product will suggest a whole regimen though (i.e., how it best fits into the sequence of chlorinating, shocking, pH adjustment, etc.)

Regards,

A. Hi A D. I just post the Q&A's, I don't even have a pool. But 4 tsp in a 24' pool shouldn't hurt anything. People seem to think about 1 part per million is appropriate (although some people don't believe in using it at all, of course). Just making sure others don't misread your comment as meaning 4 tsp for every 3 gallons -- that would be way way too much. copper sulphate is blue, so I'm not sure what's going on with your supply.

Regards,

A. The use of copper sulphate to kill algae in pools can work very well if you just keep the following points in mind.
1. A safe level of copper sulphate would be 2 parts per million
2. To prevent the copper sulphate from precipitating out of solution, chelate it with citric acid ⇦ this on eBay or Amazon [affil links] before putting it into the pool.
3. Also to prevent it from making blue stains on the pool wall, correct your total alkalinity of your pool and also see that your pH of your water stays within the correct range.

copper sulphate can be bought as a powder which is very fine and it will have a greenish color, or you can get it as a blue sugar like substance, of which the latter works best. I have been using this system for years now without any problems. You also can reduce your chlorine levels to between 2 - 4 ppm where 4 ppm would be better suited for hot climates

A. Hi Chuck. Some of us Americans love the metric system where the math is so easy. A liter of water weighs a kg, so 0.5/16000 = 0.00003125 or 31.25 ppm. copper sulphate is 25% copper, so your copper concentration is almost 8 ppm, about 4X what is considered safe. Unfortunately I don't see a good alternative to dumping 3/4 or all of the pool.

Luck & Regards,

A. Metal finishers remove the copper from their waste streams by adding sodium hydroxide to raise the pH to above 8 and precipitating out the copper hydroxide followed by filtration. You can do the same. Usually swimming pools and hot tubs have some EDTA in them, but usually not much, so you won't be able to get it all out. The higher the pH the more will precipitate out.

A. I had a hard time with algae in the pool and started using a product called PoolRx ⇨
It comes in a small blue plastic container, about cup size and oval shaped, that one can drop into the skimmer basket. The chemical used is copper sulphate Pentahydrate (chelated).

PoolRx minerals dissolve out of the unit in the first 24 hours and form a stable residual throughout the entire body of water killing algae and bacteria. This frees up low levels of chlorine or salt chlorine to be more active and available. As the minerals pass back over the PoolRx unit during circulation, they are reenergized and last up to 6 months.

My pool stays algae free so long as I brush it now and then.

A. Hi Tim. The best way to remove the iron is with a filter. If you can get a small sump pump and recirculate the water through a bucket filled with rags or pillow stuffing it will capture all of the brown color. See topic 14995 please. Good luck.

Regards,

A. Any filtering of a fresh iron water (pumped out from ground) will clog the filter within a short time period. To reduce or fully remove the iron (and/or other metals) a sedimentation of the water is needed prior to the use - in a tank 1 - 5 cbm. The sedimentation can be sped up by addition of strong dosage of chlorine (a handful) and a later addition of strong flocculator (e.g. alum 1/2 - 1 kg). Within 3 - 4 days the iron will settle to the bottom, clear water can be taken a few cm above the bottom.
Then only, a slow flow through a suitable filter (gravitation sand filter) will improve the water quality.
My ground water turns to dark brown within half an hour. With this procedure (tank 4 cbm in a height for gravitation flow on sand filter cascade) I get clear water for filling 60 cbm pool and house use.

A. Here in rural NSW Australia we can buy Stock Trough Blocks.bFarmers put them in water troughs for livestock to drink.They kill and inhibit algae. The are the size of very large soap bars. I put one permanently in the skimmer box basket. It degrades slowly over time

A. Manfred, I calculate that you would be at about 5.6 PPM copper sulphate and presuming that you are using the decahydrate version which is about 25% copper , would be a little over 1 PPM copper.

When I first cleared my pool after hurricane Irma some months ago, it took about three days at 0.4 PPM copper. So time may be on your side.

But my problem now as stated below, is a bloom of a copper resistant algae that is persisting. My online research suggests that it may be the resistant Pithophora. I need to get this solved.