Pool grout problem

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Jenny1960
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Pool grout problem

Postby Jenny1960 » Sat Jun 04, 2016 7:51 am

Good morning all,
While in the UK for 5 months our Gardner obviously did not attend our garden because, when we arrived back, the lawn had t been cut, there was debri everywhere and to top it all, the water in the pool looked like milk. However, the water is now nice and clear but the grout looks black in about 90% of the pool. Our new gardener (the previous one was obviously sacked) has been adding extra chemicals (I think chlorine) over the past 3 weeks to no avail.
Yesterday, I was sitting on the steps of the pool and scrubbed the grout with a scrubbing brush and it came off really easily. I can't do this to the whole of the pool as it's a large pool and too deep. Any ideas as to what has caused it and any solutions to get rid of it would be much appreciated please.

Many thanks in advance.....

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Re: Pool grout problem

Postby TorreDelAguila » Sat Jun 04, 2016 10:20 am

Sounds like chlorine level had plunged to next to nothing, and that has allowed bacterial/mould growth on the grouting. Cure is to boost the chlorine level to very high for week or so (it would normally be 1-3 parts per million for swimming use), but for a rapid and drastic clean-up, take the level up to 10ppm, either by adding plenty of extra multi-tablets, or by using liquid 'shock' chlorine (the latter added via the skimmer, while the pump is operating). Lots of agitation/circulation of the water will help, as will giving all the surfaces a going over with the pool brush.
Chris

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Re: Pool grout problem

Postby Jenny1960 » Sat Jun 04, 2016 4:28 pm

Thanks for your reply Chris, I'll pass all that onto oh

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Re: Pool grout problem

Postby Martin Page » Sun Jun 05, 2016 11:41 am

II had a similar problem to the one you described after some 5 years. The Black is indeed algal mould and chlorine will Kill it, as will algaecide, but it wont change colour. It will remain black. The real killer is that it is now inside the grout and you cant scrub it out.
It will not cause you any harm, If treated correctly. Its just unsightly.
The only solution is to drain, scrape, and re grout I'm afraid

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Re: Pool grout problem

Postby Torrox_campo » Sun Jun 05, 2016 1:58 pm

I think it depends on how deep the grout was affected. When we bought the house, the pool water was all green and after bringing the water back to clear, the grout was green and black. There was suggestion of acid wash but the pool needed to be drained. I persevered with high chlorine and kept brushing and filtering the water, noticing at the same time that when I brushed down the pool walls there seemed to be a cloud of the algea coming off After a couple of months I was able to get rid of the black-green grout and the pool grout now back to normal colour.
Note that I only needed to brush the pool's walls, the bottom pool was ok and you can use the chlorine tablet to clear stains on the bottom pool by moving it to the stain's locations.

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Re: Pool grout problem

Postby TorreDelAguila » Sun Jun 05, 2016 5:35 pm

Have also had that "white cloud" coming off the pool sides when brushed.
High chlorine does keep things clean: normal recommendation is 1-3ppm, but I find that 3ppm is a better level during hot months.

Also, don't go slap-happy with adding acid. It will clean things up, and dissolve limescale (tiles feel rough), BUT it also dissolves standard grout!
I have seen pools with huge stretches of grout completely missing - dissolved away.

By all means use some diluted Agua Fuerte (Mercadona is good) - diluted 1:1 or 1:3 with water - with a large paintbrush (plus gloves and covered arms!) for quickly removing the dirt that accumulates on the sides at and above the water line. Dirt will come off in seconds, but sloosh with the water and a sponge immediately afterwards to neutralise. Even working carefully like this, you will see some of your grout dissolving (milky streams coming from it).

There is such a thing as acid resistant grout. Good tile suppliers will get it for you - it's made in Italy by Technokolla, and called Epostuk. Comes in a 5-litre bucket, premixed grout paste, to which you add a precise dash of Hardener. Product is used in laboratory, public pools, commercial kitchens, and harsh environments. Life expectancy almost indefinite, and it actually adheres to the pool tiles, rather than just sitting in the gaps! Highly acid resistant. (I can post details of using it, if anyone is interested.)

Normal pool "complex" or "5-in-1" tablets contain several useful ingredients:
- chlorine and salt (anti-bacterial)
- pH stabiliser (keeps pool between pH7 and 7.6)
- flocculant (clumps dirt particles into a size that the sand filter can catch)
- water softener

pH scale:
Measure of acidity-alkalinity, on a scale of 1-14
pH1 = highly concentrated acid
pH7 = neutral (like distilled water)
pH14 = highly concentrated alkaline (like caustic soda)
A very drastic (logarithmic) scale . . . a shift of 1 unit of pH means the solution is 10 times more acid or alkaline (depending on which way you go).

Keeping the pool pH (acidity) level right is important. Ordinary tapwater can be towards pH8, and this is too alkaline to allow the chlorine to work efficiently. Chlorine action works best in a narrow band of pH. Correct dosage with the multi-function tablets will look after this.

Some folk will add agua fuerte to their pool routinely. Don't. It damages the grout, and is working blind.
Measure the pH (tester kits are dirt cheap; lab pH papers good too, if you can get the right ones) and act accordingly.
If acid needs adding (and pH+ and pH- tablets are safer) then use no more than 1-litre of a.f. at a time, poured into the flowing water stream being pumped into the pool. Do not pour into the skimmer, or pump-works - it can risk damage to the equipment if not dispersed.
As a guide, a couple of litres poured into a 8x4x2m deep pool will lower the pH by about 0.1 or 0.2 . . . quite enough for gentle 'adjustment'.
Last edited by TorreDelAguila on Sun Jun 05, 2016 8:27 pm, edited 1 time in total.
Chris

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Re: Pool grout problem

Postby El Cid » Sun Jun 05, 2016 5:44 pm

TorreDelAguila wrote:
As a guide, a couple of litres poured into a 8x4x2m deep pool will lower the pH by about 0.1 or 0.2 . . . quite enough for gentle 'adjustment'.

Chris
I would go along with that. If the pH (similar volume pool) tends into the alkaline area, I use half a 5 litre container of AF (from Mercadona) and that is usually about right. After 13 years use we have perfect grouting and the pool has never been emptied. About the only other stuff I use is Miraclear which after the pool has survived the winter, really brightens up the water quality.

A green 3M pad around the waterline usually removes any grime.

Sid

Jenny1960
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Re: Pool grout problem

Postby Jenny1960 » Sun Jun 05, 2016 6:18 pm

Really do appreciate your time in writing all that info, many thanks. I shall pass it onto my OH

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Re: Pool grout problem

Postby Torrox_campo » Mon Jun 06, 2016 9:39 am

TorreDelAguila wrote:Have also had that "white cloud" coming off the pool sides when brushed.
High chlorine does keep things clean: normal recommendation is 1-3ppm, but I find that 3ppm is a better level during hot months.

Also, don't go slap-happy with adding acid. It will clean things up, and dissolve limescale (tiles feel rough), BUT it also dissolves standard grout!
I have seen pools with huge stretches of grout completely missing - dissolved away.
I have never used agua fuerte in the pool! I have only used chlorine in tablets and granules form, I also had to add pH + from time to time as the sun and rain bring the pH level down. During the couple of months of cleaning the algea in the grout, I kept the pH level according to the test kit but raised the chlorine level higher than the ideal level.

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Re: Pool grout problem

Postby TorreDelAguila » Mon Jun 06, 2016 9:40 pm

Torrox_campo wrote:I have never used agua fuerte in the pool! I have only used chlorine in tablets and granules form, I also had to add pH + from time to time as the sun and rain bring the pH level down. During the couple of months of cleaning the algea in the grout, I kept the pH level according to the test kit but raised the chlorine level higher than the ideal level.
That all sounds perfect.
Chris

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Re: Pool grout problem

Postby USINSPAIN » Sun Jun 12, 2016 7:51 am

I have had the black algea problem added liquid chlorine seems to have got rid of most of the algea just little brown marks left, checked ph and chlorine levels ph showing 6.8 chlorine 6.1 what is the correct way to bring both these settings to the correct levels
Thank you

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Re: Pool grout problem

Postby Torrox_campo » Sun Jun 12, 2016 11:05 am

Available in DIY stores or large supermarket you buy one of these tester to check the pH and chlorine levels of your pool. Fill both tester tubes to the indicating lines with your pool water, add 4 drops each to the tester tubes, close the lids, shake then wait for about 30 seconds, Chlorine level is yellow and pH level is redish, adjust your chemicals according to the result; you will need pH plus or pH minus to adjust the pH level of your pool. Chlorine works best when the pH in the pool at the ideal level.

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Re: Pool grout problem

Postby TorreDelAguila » Sun Jun 12, 2016 1:03 pm

That's a good example of the checking kits.
In very hot weather (30decC+), you may find that chlorine at 1.5ppm isn't enough to stop green algae appearing. There is no problem with upping to 3ppm, which should clear it.
Chris

Jenny1960
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Re: Pool grout problem

Postby Jenny1960 » Sun Jun 12, 2016 5:54 pm

Great thank you!

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Re: Pool grout problem

Postby Beachcomber » Sun Jun 12, 2016 8:50 pm

Those test kits are no good whatsoever. They measure total chlorine rather than free chlorine and give wildly inaccurate results. There is a very limited shelf life on the liquid.

You need a kit like this which, although a little more expensive, is much safer and far more accurate:

Image

http://fibretechinc.com/tips-maintenanc ... r-chlorine

Furthermore, orthotolidine (OTO) has been banned in many countries as it has been linked to bladder cancer:

OTO and bladder cancer

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Re: Pool grout problem

Postby El Cid » Sun Jun 12, 2016 9:19 pm

In which case, just make sure you don't drink it!

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Re: Pool grout problem

Postby Torrox_campo » Mon Jun 13, 2016 10:31 am

Beachcomber wrote:Those test kits are no good whatsoever. They measure combine chlorine rather than free chlorine and give wildly inaccurate results. There is a very limited shelf life on the liquid.

You need a kit like this which, although a little more expensive, is much safer and far more accurate:

Image

http://fibretechinc.com/tips-maintenanc ... r-chlorine

Furthermore, orthotolidine (OTO) has been banned in many countries as it has been linked to bladder cancer:

OTO and bladder cancer
Thank you for the info. although a quick "google" with orthotolidine + cancer showed little further infomation apart from the New scientish article in the 70s.
To be fair the shelf lives of the testing liquids can last further if the testbox contains the liquids is left out of the sun, this is stated in the instruction card. There is very little contact with the liquids as the tested water, contained diluted OTO, is poured into the drain then the testing tubes are rinsed and dried ready for the next test.
However I will start using this kit costing £12 from amazon uk

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Re: Pool grout problem

Postby Lyric » Mon Jun 13, 2016 11:50 am

Cheaper in Mucky Donna

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Re: Pool grout problem

Postby USINSPAIN » Sat Jun 18, 2016 11:35 am

pleased now with the results of removing the black algae but having problems getting chlorine level at all PH reading 7.4 chlorine nothing at all dosed with half tub of granules Thursday evening checked friday morning leaving motor running all night still nothing so used other half of granules tested again this morning nothing registered, where do I go from here more granules ?????
thank you

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Re: Pool grout problem

Postby Beachcomber » Sat Jun 18, 2016 11:50 am

You should dose gradually with granular pH reducer at half a kilo a day. Chlorine granules usually come in 6kg tubs so if you used half a tub that would have been three kilos!


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