Black algae in a watersalted swimming pool

[Spellforce]

Hi,

 

For one year, I have black algae in my watersalted swimming pool:

 

 

I cant get ridd off, I used a special bottle to kill those alguaes, I brush it etc... but it always comes back after 2-3 weeks.

2 months ago I turn off the chlorinator (a few days) and I put 10kg of chlorine... without result.

 

The PH is always 7, the chlorine test is always (brown) yellow, the salt level always betweens 4.2-4.5 gr/liter.

 

I would be so gratefull if someone had a solution in how to clean it.

 

Thank you :)

 

 

 

 

[Valentine]

I have used alum before. Seems to smother it.

[sappersrest]

Some basic info that I am sure you may know already.

Firstly black spot algae is extremely difficult to get rid of , it tends to rood itself deep into tile grout unlike green algea

It involves a fair bit of time and effort to get rid of.

Obtain a pool brush with stiff bristles.

Calculate the volume of your pool this ensures that you get the correct amount of chemicals required.

A  good quality algaecide and pool water clarifier, the later is important (polyaluminiumchloride based is best, PAC)

Ensure the chemical level in the pool are as required see labels on bottles very important..

Add algaecide as directed ensuring pool is circulating.

Brush vigorously the areas that are infected, use pool vac to pic up as much debris as you can, but don't worry if  you cant

Run the pool circulation for a full 24 hours to ensure even distribution of algaecide.

Backwash filter

Add pool clarifier to the water run pool circulation for say 4 hours backwash filter, repeat this process  acouple of times.

 

DO NOT UNDER ANY CIRCUMSTANCES USE ALUM

The use of Alum in drinking and pool water is being scaled back worldwide ,The indications are that it is responsible for early onset of memory loss

The other issue is that it will seriously damage your filters health, combined with other chemicals we use in our pool will form a plaster of paris in the bottom of your filter, blocking  it up.

 

Usually black spot algae  is caused by a combination of poor circulation i.e. dead spots in the pool combined with low levels of FREE Chlorine.

you may have to increase your pool circulation times, and introduce a regime  of using an algaecide regularly or monthly or bi monthly.

The forum sponsor should be able to help you sort out the right chemicals

 

[jak2002003]

I found the normal algaecide (even the ones saying for the black stuff) have little effect on this stuff.

 

I found a very easy way to get rid of it. 

 

When the pool pump is off sprinkle a handful of chlorine powder over the top of the black algae.  Leave it to dissolve over night.  The next day its easy to use a metal brush and scrub off the dead algae... then simply turn on the pool pump and have a swim about and it will all get sucked into the filter and be gone! 

 

Of course... you must check your pool chemical balance is correct too!!!! 

[Spellforce]

 

4 hours ago, sappersrest said:

Calculate the volume of your pool this ensures that you get the correct amount of chemicals required.

A  good quality algaecide and pool water clarifier, the later is important (polyaluminiumchloride based is best, PAC)

I realize now that I didn't understood that english metric: "6 oz per 5000 gal" = 0.00898698205 kg / m³

My sw. pool is 100m3 si I had to use 0,9 Kg of algaecide.

3 times I only used 3 glasses of algaecide. Luckily I had 1 liter left, I just emptied the algaecide bottle.

 

Do you think that algaecide is good ?

 

 

 

4 hours ago, jak2002003 said:

When the pool pump is off sprinkle a handful of chlorine powder over the top of the black algae.  Leave it to dissolve over night.  The next day its easy to use a metal brush and scrub off the dead algae... then simply turn on the pool pump and have a swim about and it will all get sucked into the filter and be gone!

I can use 15kg of chlorine and dont use my swimming pool for 1 week.

But a too high level of chroline may damage my chlrorinator ?

Do you have also a watersalt swimming pool ?

 

 

[jak2002003]

4 minutes ago, Spellforce said:

 

I realize now that I didn't understood that english metric: "6 oz per 5000 gal" = 0.00898698205 kg / m³

My sw. pool is 100m3 si I had to use 0,9 Kg of algaecide.

3 times I only used 3 glasses of algaecide. Luckily I had 1 liter left, I just emptied the algaecide bottle.

 

Do you think that algaecide is good ?

 

 

 

I can use 15kg of chlorine and dont use my swimming pool for 1 week.

But a too high level of chroline may damage my chlrorinator ?

Do you have also a watersalt swimming pool ?

 

 

Yes.  We have a 'salt water' swimming pool.  Also had one at the last house.

 

You only need to put a small amount of the powder chlorine over the top of the black algae areas.. not put a lot into the pool...  You can use the pool the next day.. because you only will add a tiny amount. 

[Spellforce]

1 minute ago, jak2002003 said:

Yes.  We have a 'salt water' swimming pool.  Also had one at the last house.

 

You only need to put a small amount of the powder chlorine over the top of the black algae areas.. not put a lot into the pool...  You can use the pool the next day.. because you only will add a tiny amount. 

Thank you Jak, I'll do that after the algaecide treatment.

On that bottle I've read in maintenance treatment "3oz per 5000 gal" = 1/2 liter per week = one 2 liters algaecide bottle per month (2000 bahts)... chlorine (100 bahts per kilo) is much cheaper ! :)

[janclaes47]

19 hours ago, Spellforce said:

The PH is always 7, the chlorine test is always (brown) yellow

I would start with a decent testkit, because the standard testkits with the 2 tubes only test for total chlorine, and it is the free chlorine you have to test because that is the effective one.

 

You can have 5ppm total chlorine and but if it is all combined chlorine it is useless.

[Spellforce]

1 minute ago, janclaes47 said:

I would start with a decent testkit, because the standard testkits with the 2 tubes only test for total chlorine, and it is the free chlorine you have to test because that is the effective one.

 

You can have 5ppm total chlorine and but if it is all combined chlorine it is useless.

It might be the reason ... what do I need ? an electronic testkit ?

[janclaes47]

Just now, Spellforce said:

It might be the reason ... what do I need ? an electronic testkit ?

Get on Ebay a Aquachek 7 in 1 or silver kit of test strips.

[Spellforce]

Thank you everyone for your advices :)

My first mistake is not to be familiar with the US metrics, my fault !!!

 

I will give a feedback in a few days, the time to see if that black algae algaecide is effective or not when I add one liter (and not only 3 glasses).

[grollies]

@Spellforce I got the same problem for the last two weeks.

 

Brush, vacuum, Brush, vacuum, Brush, vacuum, Brush, vacuum.

 

My biceps are noticeably improved since brushing this shit off daily.

 

Got a fine wire brush to go on the end of my brush pole, does a much better job of cleaning the black algae than the stiff nylon brush.

 

From what I've read, using chlorine powder doesn't kill the algae as it has a hard 'shell' over the top of it. 

 

@jak2002003 was probably getting good cleaning from using a wire brush, but it worked for him so may give it a go also.

 

The main reason my pool started black algae was my failure to vacuum for 3 weeks....... plus free chlorine was low.

 

Try cleaning your cell in a weak hydrochloric acid solution, my cell is working much better now. Plus @sappersrest is totally correct, your chems need to be balanced. Most of all, brush and vac twice a week.

 

Black algae is a bastard to get rid of, see how we get on.

 

BTW, I used that algaecide you've got but on SR's recommendation I got this. I'll let you know if it's any better.

 

For 100,000 litre pool initial treatment 10oz per 5,000 galls = 1562ml

 

Then 780ml (5oz per 5,000 gall equivalent).

 

 

 

 

Edited June 24, 2017 by grollies

[sappersrest]

Add pool clarifier to the water run pool circulation for say 4 hours backwash filter, repeat this process  acouple of times.

Sorry forgot to mention why.

After you have brushed the pool all the algae will mix in with the rest of the water, the reason we use the clarifier is to coat all the small particles so they become large enough for them to be caught in the sand ,filter otherwise they may well go straight the sand and back in the pool.

[luudee]

I've had good luck with copper oxide (sold as a blueish powder in most pool shops).

 

Once a month seems to do the trick for me. about 0.5 KG for my pool (270000 liters).

 

Also salt pool ....

 

rudi

 

[Naam]

15 minutes ago, luudee said:

I've had good luck with copper oxide (sold as a blueish powder in most pool shops).

what you are using is copper sulphate (Cu2SO4). the colour of copper oxides are red (Cu2O) or charcoal to black (CuO).

[luudee]

22 minutes ago, Naam said:

what you are using is copper sulphate (Cu2SO4). the colour of copper oxides are red (Cu2O) or charcoal to black (CuO).

 

Ahh, thanks for the correction Naam !

 

rudi

[sappersrest]

Use copper sulphate with great care

The maximum level for copper is 1.0ppm,  lower levels are recommended. At high concentrations, the copper deposits out of the water and onto hair, fingernails , bathing costume or pool walls causing green stains. High levels of copper can also cause green water.

Staining also increases greatly if the pH is above 7.3.

 

 

[janclaes47]

1 hour ago, luudee said:

I've had good luck with copper oxide (sold as a blueish powder in most pool shops).

 

Once a month seems to do the trick for me. about 0.5 KG for my pool (270000 liters).

 

Also salt pool ....

 

rudi

 

 

Half a kilo every months???

 

I bet they call you the green hair family with no teeth ine the village.

 

You know that copper builds up in your water and is highly poisonous?

[Spellforce]

On 25/06/2017 at 1:43 PM, luudee said:

I've had good luck with copper oxide (sold as a blueish powder in most pool shops).

 

Once a month seems to do the trick for me. about 0.5 KG for my pool (270000 liters).

 

Also salt pool ....

 

rudi

 

Are you sure that copper sulfate is compatible with a waltersalt swimming pool ?

2 years ago I had to change my electrolysis , I suspect the cause was the use of copper sulfate.

 

http://caribbeanpools.com/pool-care-salt-water-faq.html#copperalgicides

Quote

Can copper based algicides be used in pools equipped with a chlorine generator?

It depends on the product. Many copper based algaecides contain copper triethanolamine. Triethanolamine is a nitrogen containing compound which is not very chlorine tolerant. Therefore, once inside the chlorine generator cell, this compound will break down resulting in free copper which has the potential to stain. This condition can result in copper based scale on the chlorine generator cell plates. In addition, because triethanolamine contains nitrogen, as it breaks down it has the potential to contribute to chloramine formation. Just as with certain sequestering agents, the use of these types of compounds will cause the active ingredient to be destroyed and could result in problematic compounds being formed.

 

 

[Spellforce]

On 24/06/2017 at 1:17 PM, grollies said:

@Spellforce I got the same problem for the last two weeks.

 

Brush, vacuum, Brush, vacuum, Brush, vacuum, Brush, vacuum.

 

My biceps are noticeably improved since brushing this shit off daily.

@jak2002003

@sappersrest

 

ahah :)

Me too 2 days ago, I also have spend 4 hours to brush + vaccuum.

 

Yes that will be good to compare our results in a few day: you green algua algaecide + clarifier  VS black algua algaecide

 

 

PS: luudee mentioned the use of copper sulfate but I scare to damage the electrolysis.

[Spellforce]

A quick update that may help people who will have the same problem.

 

1 week ago I added 1 liter of black algua algaecide (for a 100m3 sw. pool, 1800 bahts the 2 liters bottle) and I add more salt (to the level of > 4.5 gr per liter).

 

That worked ! :)

 

I have no more new black alguas (but I have still some small old black alguas, that takes times to clean it everywhere)

[grollies]

2 hours ago, Spellforce said:

A quick update that may help people who will have the same problem.

 

1 week ago I added 1 liter of black algua algaecide (for a 100m3 sw. pool, 1800 bahts the 2 liters bottle) and I add more salt (to the level of > 4.5 gr per liter).

 

That worked ! :)

 

I have no more new black alguas (but I have still some small old black alguas, that takes times to clean it everywhere)

Nice one mate. I'm going with @sappersrest and getting my pH down and sorting the CYA level as after re-test I have very little.

 

Also some total chlorine but no free chlorine . After pH settled got some chlorine conditioner to add then see if the free chlorine rises.

 

Once I get some free chlorine then I'll go back to add more algecide and carry on cleaning.

 

Glad you got it sorted. 

[Spellforce]

On 02/07/2017 at 6:13 PM, grollies said:

@sappersrest

Glad you got it sorted. 

Thank you :)

But I dont know what really worked ? Black algaecide or > 4.5 gr of salt per liter or ...both ?

 

I dont like to add additional products as algaecide. I think (but I'm not sure) that of lot of salt (> 4,5 gr/L) + pump/chlorinator running more than 12h/days for a week can kill everything (safer for the water and cheaper than a bottle of Black algaecide ).

[grollies]

2 hours ago, Spellforce said:

Thank you :)

But I dont know what really worked ? Black algaecide or > 4.5 gr of salt per liter or ...both ?

 

I dont like to add additional products as algaecide. I think (but I'm not sure) that of lot of salt (> 4,5 gr/L) + pump/chlorinator running more than 12h/days for a week can kill everything (safer for the water and cheaper than a bottle of Black algaecide ).

I'm the same mate, didn't want to add anything except salt. But had to add algaecide eventually - hopefully only once. Then realised had to add CYA to stabilize the chlorine levels.

 

CYA now about 20ppm, will increase to 40ppm. Eventually got some free chlorine now.

 

My chlorinator has an output to an acid dosing pump so got pH back to normal.

 

Unfortunately you have to treat pool water, especially outdoors.

 

Thanks to @sappersrest though for his input.

 

Black algae all but gone for now, fingers crossed.

[Spellforce]

Up !

 

Unfortunately the black algaes are coming back !

(the black algua algaecide  bottle @2000 bahts was a temporary solution)

 

Maybe Copper Sulfate is best and cheaper solution ?

But as I asked before, is it 100% safe ot use Copper Sulfate with a salted swimming pool ? (I really scare to domage my electrolysis)

[grollies]

I found adding CYA (cyanuric acid) combined with setting up my acid dosing pump properly has greatly improved my pool water.

 

Tested two days ago, about two months after increasing the CYA the results are as follows:

 

Salinity: 4000

Cy: 40

FCl: 3

Alkalinity: 80

pH: 7.8

Total hardness: 100

 

You should not have to add salt unless you've been heavily diluting the pool water.

 

I have not used the black algecide treatment for two months after the initial treatments.

 

I have found that once you get the balance right the pool (with regular cleaning) looks after itself.

 

As Sappersrest said before, get a decent test kit and it's FREE chlorine level that is important to keep killing of the algae.

 

No more black algae.

[janclaes47]

18 minutes ago, grollies said:

Salinity: 4000

Cy: 40

FCl: 3

Alkalinity: 80

pH: 7.8

Total hardness: 100

 

I think your pH is a bit to the high side to make you chlorine effective.

 

Between 7.0 and 7.4 would be ideal, with the lower the better in a salt pool.

 

@ the OP, the solution to your problem has been posted a few times already.

 

In short, get your water balance sorted out, and scrub.

[Spellforce]

19 hours ago, grollies said:

As Sappersrest said before, get a decent test kit and it's FREE chlorine level that is important to keep killing of the algae.

No more black algae.

I have good test kit:

- salt 4.7 gr/L

- PH = 6.8

... but I've stll have new black algaes.

 

Yesterday I spent of lot of time on Google, what I've founded:

- Copper Sulfate is compatible with salted swimming pools

- Chlorine can not kill black algaes, Copper Sulfate is mandatory with a salted SP

- Copper Sulfate kills alguaes, but you have to take care about the volumes: fist time only a glass for a 100m3 SP, then every 2-3 days only 2 spoons untill they are killed. For maintenance no more than 2-3 spoons per months

 

I'll try it tomorow and post here the result.

 

[janclaes47]

54 minutes ago, Spellforce said:

I have good test kit:

- salt 4.7 gr/L

- PH = 6.8

So with your test kit you can measure Total hardness - Total chlorine - Free chlorine - Total alkalinity - pH and Cyanuric acid?

 

54 minutes ago, Spellforce said:

Chlorine can not kill black algaes,

 

If you say so.

 

54 minutes ago, Spellforce said:

Copper Sulfate is mandatory with a salted SP

Strange that in my 7 year old salt water pool, I have never added any copper sulfate, and never had algae.

 

But you're probably right about everything, and all the other that advised you are wrong, and that's why this thread already exists for months.

Edited September 28, 2017 by janclaes47

[Spellforce]

3 minutes ago, janclaes47 said:

So with your test kit you can measure Total hardness - Total chlorine - Free chlorine - Total alkalinity - pH and Cyanuric acid?

- "Total Hardness"; as long you didn't use a lot of chemical products, your water wont be "hard"

- Free Chlorine: as long as you pH is low and even a little acid in a tropical country as Thailand (pH < 7), then the "Total Chlrorine" indicator is enough

- Total alkalinity = Total hardness

- pH never more than 7.2 -7.3

- "Cyanuric acid": for what ? When you have a salted SP you don't need to use a lot of acids, so the CYA is always low

 

What I"ve read yesterday is that black algaes like salted SP and that the "free chlorine" wont kill those algaes. Only copper sulfate can kill those algaes but dont use it too much or you will have green hairs :)