REALLY, REALLY Bad ALGAE problem

[Gerry]

Hi All
I came accross this site whilst searching in desperation for information.

I live in Southern Italy, near Brindisi.

I'm retired and to fill in the long hours of wall to wall sunshine, I started looking after a few swimming pools.

I devoured every piece of information, bought the biggest pool robot and electronic water testing equipment and now have a fantastic time cleaning and maintaining 7 pools.

6 of them are fantastic and I have to say that I love the accolades from guests saying how nice it is to have such a well maintained pool.

OK, my problem.

One pool is just about impossible to keep clean.

It is situated in a well maintained garden, surrounded by a 3m wall.

3 weeks ago I had a call to say that the pool was turning green. I had only cleaned it the day before.

On arrival, the pool was not turning green, IT WAS DARK GREEN. (I'll attach a few piccies at the end of this saga)

This was the fifth time this year this has happened to this pool.

This was the worst and the quickest. In 24 hours it had gone from clear sparkling clear water, to thick slimy pea soup.

All chemical levels are OK.

I spent a week getting it back into shape and ended up with clear sparkling water again.

Today, we have guests arriving from Norway, so yesterday, I spent 3 hours cleaning, scrubbing and preparing what was already a pretty clean pool.

I finished at 2pm, I returned at 4pm, just two hours later and could see the bottom of the pool already starting to be covered in green algae.

This morning, I returned to clean it again before the guests arrived and the whole bottom was covered. Fortunately, it had not started to turn the water green yet and so I was able to clear it out very gently without it clouding up.

I have taken samples of the water and had it analysed in a local water laboratory, who have confirmed that the green is of a vegetable origin.

They have also told me that this algae is actually eating the chlorine and thriving on it.

OK, so now for my question.

1 . Can algae be introduced to the water from surrounding vegetation. :?:

2 . Would it be possible to actually add algae in whatever form to a swimming pool. :?:

3 . If, this is some weird naturally reacurring problem that is so virulent that it can cover a 12m x 6m x 3m, deep pool, in hours, how can I kill it. :?:

Below, a few piccies of the pool at its worst.

Thanks for reading this, sorry its a bit long, but I thought that a bit of background information might be of help.

Best wishes from SUNNY Puglia, Italy.
Gerry
[attachment=2:i3mnuy0z]Keith-Swimming-pool.jpg[/attachment:i3mnuy0z]
[attachment=0:i3mnuy0z]Keith-Swimming-pool-3.jpg[/attachment:i3mnuy0z]
[attachment=0:i3mnuy0z]Keith-Swimming-pool-3.jpg[/attachment:i3mnuy0z]

 

[Bama Rambler]

Welcome to TFP Gerry.

You have just regular green algae. It can be eradicated and kept away by following the advice here.
Read Pool School and absorb as much as you can then keep reading till you have a good grasp of how to keep a sparkling pool.

Saying that the chemical levels are OK doesn't tell us anything. We need numbers.
pH
FC
CC
TA
CH
CYA

CYA (aka stabilizer) is a very important test and one of the hardest to get right.
Post those numbers and we can help you clear this pool and keep it clear.

 

[dmanb2b]

Welcome to TFP Gerry What are you using for chlorination?

Can you post the test results?

FC
CC
PH
TA
CH
CYA

That pool needs liquid chlorine and lots of it...here are some articles from pool school you should read

pool-school/pool_water_chemistry
pool-school/shocking_your_pool
pool-school/defeating_algae
turning-your-green-swamp-back-into-a-sparking-oasis-t4147.html

 

[Gerry]

Thanks for the interest and replies.

My last lot of readings, which have been fairly constant throughout this saga with this pool are:

Chlorine - 1.4
PH - 7.1
Alkaline - 0.85

As for all of the other readings you asked for I have no idea, nor how to check for them.

I hope the above helps, but just to remind you, that none of the other pools have any problems at all, only this one.

SPOOOOOOOKY...

PS,
I've just read the first few lines on your pool school page about defeating algae and it says that if the chlorine levels are kept right then this shouldn't occur, the problem is that according to the test lab I sent the samples to, this algae is ACTUALLY EATING THE CHLORINE AND THRIVING.

Spoooooookier than ever

 

[dmanb2b]

this algae is ACTUALLY EATING THE CHLORINE AND THRIVING.

Either the lab did not explain things to you properly or you need to stop using such a lab. Chlorine kills algae...period. You are likely just not adding enough. If shocking does not clear up the pool, then it's not algae.

What form of chlorine are you using for chlorination? ie...chemical name.

 

[X-PertPool]

it looks like the water is clear and the algae is stuck to the bottom of the pool. I would vacuum out what you can on waste, brush what didn't vacuum up and then shock

 

[vln]

Algae will eat chlorine at low levels.

I would shock the pool and hold it at 20 ppm until it holds that level of chlorine throughout the night. make sure to vacuum and clean the filter whenever the pressure rises more than 7 psi. What is your CYA at? You may need to shock to a higher ppm if it is high.

 

[chem geek]

You need to understand that algae does not eat chlorine, but that chlorine does get consumed (converted to chloride salt) when fighting algae. So when there is a lot of algae present, chlorine usage goes up. However, the rate at which chlorine is able to kill algae is dependent on the active chlorine level and that depends not only on the Free Chlorine (FC) level but also on the Cyanuric Acid (CYA) level.

If you have been using Trichlor tabs for chlorination and/or Dichlor powder/granules, then your pool's CYA level is probably very high. When the CYA level is high, it takes a proportionately higher FC level to kill or prevent algae from growing. With very high CYA, it is more practical to reduce it by doing a partial drain/refill. So you see how important it is to get an accurate CYA reading.

You should get yourself a proper test kit. In Europe, you should be able to get a Palintest Pooltester SP 315C (make sure it's the 315C and not the 315).

 

[Gerry]

I use an 'AQUACHEK' meter which gives me three readings.

Ch - PH - ALK

I've used it for about three years and apart from the problem with this particular pool have had absolutely no other problems with chemical levels.

I think that the answer is something obscure, but have no idea what it could be.

Hopefully, someone will be able to think of a solution.

Thanks for all your interest.
Gerry

 

[teapot]

I use an 'AQUACHEK' meter which gives me three readings.

Ch - PH - ALK

I've used it for about three years and apart from the problem with this particular pool have had absolutely no other problems with chemical levels.

I think that the answer is something obscure, but have no idea what it could be. It's nothing obscure
Hopefully, someone will be able to think of a solution.

Thanks for all your interest.
Gerry

Oh dear Gerry, you have an electronic aquachek strip reader, yes?
Your first port of education is Pool school, click on the button (top right of the forum)
You MUST test for cyanuric acid (CYA) you also need to test all the other parameters, sadly your Aquachek is really not up to the job, sure they are ok when things are running well but when things go wrong you need to know what's gone wrong and you don't have the information available.

If you like others are using multi action tablets, these add other chemical like CYA that can build up over time and lead to the sort of problems you are experiencing, You must shock the pool with more chlorine from a source that does not add more cyanuric acid, like plain bleach or sodium hypochlorite from a pool shop. Get the pool to 10ppm of chlorine and hold it there as a starting point whilst you get a better test on the water.

 

[zea3]

I use an 'AQUACHEK' meter which gives me three readings.

Ch - PH - ALK

I've used it for about three years and apart from the problem with this particular pool have had absolutely no other problems with chemical levels.

I think that the answer is something obscure, but have no idea what it could be.

Hopefully, someone will be able to think of a solution.

Thanks for all your interest.
Gerry

Gerry, welcome to TFP! The answer is not obscure. Without knowing the CYA level of the pool you do not have the whole picture of what is going on in the water. If you or whomever maintained the pool before you have used stabilized chlorine products, then the CYA (stabilizer) is likely too high. CYA provides a layer of protection to shield the Free Chlorine from burning off prematurely due to exposure to the sun, much like sunscreen protects your skin. CYA and Free Chlorine need to be maintained in proportional levels. You cannot sanitize a pool when the FC is 2 but the CYA is 100. The FC is "smothered" by the CYA and is not available to kill organic matter in the water, such as algae. When CYA is too high, the Free Chlorine levels needed to sanitize the pool must be maintained high enough to overcome the "protective" effects of the CYA. If you plug the test results into the pool calculator you will see how much FC you need proportional to the CYA level of your pool. For my example, a pool with 100 CYA would need a daily FC level of 5-7 and to shock the pool you would need to keep the FC at 15 until you passed the overnight FC loss test.

If you do not want to buy a new test kit, then please consider finding a supplimentary kit to test CYA.

This website is very active and there is thread after thread describing different pool owners experiences clearing up pools full of algae. It can be done with liquid chlorine applied at the appropriate levels.

 

[anonapersona]

"well maintained garden" makes me wonder if fertilizers have gotten into the pool.

 

[Ohm_Boy]

All chemical levels are OK.

No. They're not.

I think that the answer is something obscure, but have no idea what it could be.

The answer is simple, not obscure. And you have been given more than an idea.

Hopefully, someone will be able to think of a solution.

We have the solution. It lies in the chemistry of the pool, tried, proven, and true.
I'm sure that the minimal testing you are doing works in a few pools, but just because it doesn't work for one does not mean that there is some dark magical element at work. It is simply a combination which requires a little more than what you are doing. You are almost certainly using a stabilized chlorine source, and you really need to understand the relationship between stabilizer level and chlorine effectiveness. It is this relationship which is the missing piece of your puzzle. Your algae is not thriving on chlorine, it is just outnumbering it. It is simply growing faster than you are killing it, because you do not have enough chlorine in your water.

If you will not hear what we know to be true in pool chemistry, then I suggest you look to replace half or more of the pool water with fresh, brush and vacuum as much algae out of the pool as possible, and maybe dump a few hundred Euros worth of phosphate remover in it.

But we know better. All you need is chlorine. And an open mind.

 

[indio1919]

Just shock it with 20lt of Chlorine! Your Chlorine level is far to low man. I look after over 50 pools and chlorine shock is the best treatment in this kind of situation.