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Volcanic ash?


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We were away from home for a month, during which the Icelanders carelessly lost control of their volcano.  While we were away the pool was filtered for several hours a day on a timer, and some friends came in from time to time to check the chemicals and make sure the filter wasn't blocked.  When we got back the water looked OK.

We immediately started doing two things, several times a day, that hadn't been done in our absence: (1) backflushing the sand filter, and (2) running a robot cleaner (the kind that moves around the bottom and walls of the pool, pulling water through a filter bag).

We found that every time we changed the the robot's filter bag it was coated with a very pale creamy substance, which was easy enough to rinse off, but which doesn't seem to be getting any less.  And the initial outflow from the sand filter during backflushing is cloudy but a similar colour - almost white.   In the pool itself we can see what looks like pale dust where the water flows over the edge tiles (it's an overflow pool) and sometimes we can see something similar on the bottom, before the robot has stirred up the water and made it cloudy.

We can only think of two possibilities: either volcanic ash from Iceland, or some pool chemical that has failed to dissolve.  The white coating that it leaves on the area around the filter outflow is washed away by a simple rain shower, and neither the pump nor the robot shows any sign of getting clogged or jammed.  It isn't unpleasant to touch or smell; I've swum in the pool several

times with no ill effects.  But it doesn't seem to be going away.  

Does anyone have any suggestions about what it might be, and whether we should be doing something about it?

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[quote user="Poolguy"]Where is the pool?[/quote]

Do you mean geographically?  (in Lot-et-Garonne)

- or physically? (it's an in-ground pool in a garden but close to the house, tiled, 25 years old, but showing no cracks or leaks)

[quote]What are your chemistry measurements (all 4 please)[/quote]

Sorry for my ignorance but my testing kit only shows me three: pH is 6.8 - 7.0; free chlorine is about 1; TH is between 250 and 500.

Is this enough?

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OK

Lot et Garonne = hard water area

You have Calcare. Now that you have an acid pool (pH below 7) all of the calcare has come out of solution and is depositing on the bottom.  So drop the pH a fewmore points (temporarity) and

use the remedy to vacuum to waste till you can see the bottom and its clean. Then Raise the pH again to 7.2 - never swim in a pool  with a pH under 7

The only way to prevent happenings such as this in the future is to use rain water for your top up and then adjust the Alkalinity levels manually.

By 4 paramaters I mean the following: pH, Chlor Free, Total Alkalinity, Cyanuric Acid. Without be able to test for to determine these levels in a pool it is IMPOSSIBLE to manage a healthy pool.

If you want to get better water then you'll need to change the sand to zeolite, it will help with the calcare to some extent. I can help you with your problem if you want but you need to PM me.

Andrew

 

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Hi Allanb,

It would be useful to know your Total alkalinity (TA) too, this can be done with either an additional test kit or even the dip strips which seem to be reasonable at measuring TA.

Very important is to find out your Cyanuric acid level (CYA) as you are using multifonctions and the dip strips cannot measure that accurately, ( recently tested 3 pools with 190ppm 160ppm & 140ppm and dip strips from several manufacturers showed 20-30 and 0

I would suspect that your free chlorine (FC) level is also too low as you use multifonction gallets which add roughly 5-6ppm of Cyanuric acid (CYA)  per tab, after 7 gallets you have enough CYA in the pool and do not need anymore. CYA is needed to prevent the sun from burning up the chlorine during the day but too much is also bad as it binds to the chlorine to protect it and therefore there is not enough active chlorine to keep your pool safe. If you can, switch to using Javel (bleach) sold in brico's for around 18€ for 20 litres that way you will add just chlorine to your pool although you will need to add some PH- from time to time.

From what you have sent, your PH is a little low(6.8-7.0) target (7.4-7.6) and that can pull calcaire out of solution, lowering your TA, and causing more PH fluctuations, do you have any heaters etc?  Is your pool a vinyl liner or concrete/plaster/tile? and how big in m3 (so I may be able to guide you in amounts)

EDIT: Morning Andrew [:)]

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Many thanks to you both.  I'll get to work on the chemical part of your advice, which obviously includes getting some better testing kit.

[quote user="Théière"]Do you have any heaters etc?  Is your pool a vinyl liner or concrete/plaster/tile? and how big in m3 (so I may be able to guide you in amounts)[/quote]No heaters.  The pool is concrete and tiles - no liner.  I estimate the volume to be 65-70 m³. 

[quote user="Poolguy"]The only way to prevent happenings such as this in the future is to use rain water for your top up and then adjust the Alkalinity levels manually.[/quote]I should perhaps have mentioned that almost all of the top-up water comes from a well; obviously rain falls on the pool, but I don't have any way of collecting it from elsewhere.  Do I need to be concerned about the difference between rain and well water?

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[quote user="allanb"]I should perhaps have mentioned that almost all of the top-up water comes from a well; obviously rain falls on the pool, but I don't have any way of collecting it from elsewhere.  Do I need to be concerned about the difference between rain and well water?
[/quote]

YES , by any measure using ground source water for a pool is the WORST choice as you have experienced, it comes to along with a vast variety of minerals - in your case lots of Calcare (at least). You are better off using mains water as the cost of treating the water from the well to bring it up to the standard you need for your pool will outweigh the cost of mains water.  Moreover, as your pool is concrete and tile, if you don't keep your TA well checked then an Acid pool or a pool with low TA will actually start to dissolve the grouting between the tiles and you've then got a leak. It’s a slippery slope from there to the complete disintegration of the tiling and waterproofing of the pool. From there your only choice will be to refit with a liner, the cost of which will certainly get your attention.

I recommend that you need a SCUBA to keep tract of all of these parameters and a good book on pool management.

Andrew

Morning John, hope you are well this morning.

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Poor Allan, you are really taking a pasting this morning [:)]

Without an analysis of the well water which will also changes during the seasons, you are not really sure what you are adding in addition to H2o.  Wells can be a source of iron, magnesium and high phosphates none of which you want. Liner pools are more tolerant of additions generally. With concrete/plaster/tiled pools there is often and especially after brushing of the walls (standard cleaning procedure) a high PH produced (not in the bulk water but right on the wall/floor)  If metals are present any PH of 8.3 or above causes these to drop out of suspension and possibly stain the pool walls/floor. Your multifonction gallets could quite possibly contain copper (little blue flecks) visible in the gallets, this like CYA can build up over time and can result in staining usually green/blue. The copper is put there as it can help with combating algae although the proper level of chlorine will do this too it is an insurance in case the chlorine gets low. I have used copper in my liner pool for 5 years very successfully although I control the level very precisely.  I would NEVER use copper based products in any concrete/plaster/tile pool.

As Andrew has said your low PH is pulling your pool apart.

Andrew mentioned the scuba+ it is a great little tester and manufactured by one of the most respected names in water testing Lovibond the other being Palintest, as you need to maintain the TA and balance of your pool water more closely than a liner pool it would if the budget allows be a sound investment.

(Thanks Andrew, yes not too bad after first load of treatment)

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I think I'll just fill the pool with concrete, add some gravel, and use it as a place to play boules.

No, really, I appreciate the advice.  I have invested a few euros in a 4-element testing kit, which shows a

"normal" reading for cyanuric acid and a pH level which has gone up a

bit in 2 days : now around 7.8.  I take this as a mildly hopeful sign.

My task for today is to suck up as much as possible of the deposit with the vacuum device and flush it away.  In the last couple of days it seems to have accumulated much less, so I've optimistically put on hold your suggested procedure of dropping the pH temporarily. 

I've also, until further notice, given up using the well as the top-up source.

For future use I'll investigate the SCUBA+ (it isn't in my local pool shop). 

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[quote user="allanb"]I think I'll just fill the pool with concrete, add some gravel, and use it as a place to play boules. [:D][:)][:D]


For future use I'll investigate the SCUBA+ (it isn't in my local pool shop). 
[/quote]

Sadly good testing equipment is not for sale in a lot of pool shops although bad ones are. I sometimes wonder if it is let the customer think they know whats going whilst relieving them of a few more € for another chemical magic bullet.

Test equipment is expensive and certainly that may also be the reason it is not stocked The only companies worthy of looking at are Lovibond, Palintest or Hanna and out of all of them the scuba+ is the best/cheapest option, I sometimes wish I had one, it cost almost as much to re-calibrate my Palintest pooltest 9 as it does to buy a scuba+

Good luck with the vacuuming.

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[quote user="AnOther"][quote user="Poolguy"]never swim in a pool  with a pH under 7[/quote]Sorry to be boring with naive questions but why ?

[/quote]

Generally because of skin, eye and mucus irritations. Most notably eye though as tears have a PH around 7.4 it causes less irritation at that level.

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[quote user="Poolguy"]

YES , by any measure using ground source water for a pool is the WORST choice as you have experienced, it comes to along with a vast variety of minerals - in your case lots of Calcare (at least). You are better off using mains water ......[/quote]

I know almost nothing about this subject, but the communal water supply here, and probably in a lot of other places, comes from a borehole (or two), which to my way of thinking is also a ground source. How do they get the vast variety of minerals out of it?

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[quote user="Théière"] Test equipment is expensive and certainly that may also be the reason it is not stocked The only companies worthy of looking at are Lovibond, Palintest or Hanna and out of all of them the scuba+ is the best/cheapest option, I sometimes wish I had one, it cost almost as much to re-calibrate my Palintest pooltest 9 as it does to buy a scuba+[/quote]

Bless you John

Andrew

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