pool test

[Krill]

We have had a chlorine pool for 3 years with little trouble but the last few days when I test the chlorine the colour turns bright orange! instead of the usual yellow tints, any ideas please ?????

[Poolguy]

Krill

Bright Orange?

Its news to me, if your doing everything normally, I'll check with our technician.

How old is your testing kit?

Did you test several times in different parts of the pool?

Have you Choc - ed recently?

Have you renewed a good proportion of the water each year?

I'll get back to you.

Andrew

[Krill]

Thanks for that Andrew, I tried a new test kit with the same results, the water is very clear and ph is spot on, the pool has had a lot of use in the last week so i'm thinking it could be something from sun tan lotion or other types of cream, will test again and let you know

[Poolguy]

Krill

Are you using the drops or the tablets to measure Chlorine?

If its drops, then you should be using tablets and I recommend that you go to your supermarche or Brico and buy some testing tablets, DPD1.

If you are using these, then they will measure Active chlorine as opposed to total chlorine, there is a big difference. To measure total chlorine you'll need DPD3 tablets, but no need for that just yet.

With this test you should get a reading from slightly pinkish water which indicates low chlorine up to vivid red water which is too much chlorine.

If you get some other colour with this test then you'll need to post again and we'll try to analyse the problem. If you can take a pic of the test and email it too me it might help to analyse.

I would not like to speculate on the vivid orange as there are too many possibilities - One being the wrong tester, another is that there is too much chlorine, and many more possibilities.

At any rate its not to grave situation I think.

Andrew

[Krill]

Hi Andrew

Thank you for all your help, yes I am using the liquid tester and for the last 3 days have had the same results but today everything is fine with the readings spot on, I havent done anything to the pool chemicals so i dont understand what has happened. I will test it daily and see what happens, also this year I have had to use a lot of ph + but in previous years I only needed ph -

Who knows

[Poolguy]

Krill

glad it sorted.

But get some of the tablets instead of the liquid. At the moment you are only test for total chlorine instead of 'active' chlorine. Its not the same thing. You might be saturated with stabilizer and using too much chlorine to get the right reading.

There's an explaination for everything ... somewhere.

Even to the question "why did God invent flies"?

Andrew

[The Riff-Raff Element]

Have you changed out the water at all over the last three years? If you've been keeping the chlorine level on the high side then it is likely that you are building up a concentration of cyanuric acid (a breakdown product from the chlorine chemical you are probably adding to the pool to sterilise it). This itself is broken down by biological action, but if you've been over egging the chlorine there won't be any biology in the pool to do it... This would also explain why you've had to reverse your pH treatment regime.

You could test this by cutting your back chemical addition and reducing the level of active chlorine in the pool to a minimum (about 0.5 ppm - use DPD tablets to test and test a lot as there is probably three years worth of urea in the pool from sweat and piddle and this is a fine fertiliser for algae!) - the cyanuric acid itself should then start being broken down and pH should stabilise or even start to rise again.

To be honest, the above is a lot of hard work, slightly risky from the green water point of view, and if everything else is good I wouldn't worry too much. You could try changing out say 50% of your water to dilute the soup a bit but then you would have to rebalance the water again (are you in a hard water area by the way? This could also be a reason for having to reverse your pH treatmant after a couple of years). Speaking as a chemist, I prefer electrolytic sterilisation and saline pools mostly because the whole business of keeping them healthy is easier, so you could consider a change to that system.

All the best, Jon

[Poolguy]

It an interesting analysis Jon

I am interested in the reasons why you think that using a salinator to generate chlorine is a 'easier'. As I understand it, a salinator will generate the same amount of chlorine no matter what the demand is.

Are you aware that automatic pool controllers exist which manage the balance of acidity and chlorine concentration to near perfect levels no matter what the temperature of pool usage is. This is all managed and controlled without any intervention by the owner, save checking the drums are full and the odd test to double check. Which is easier, to my mind its that later.

I concur that the pool water problem experienced by Krill was most probably an over concentration of Stabiliser and undissolved solids caused by over chlorination. Can you propose any chemical reason why the test sample was orange, as it should be in the yellow range using the liquid reagent. If it was in the brown -red region then its contamination by acid reagent, but Orange...?

Thanks for contributing your professional expertise.

Andrew

 

 

[The Riff-Raff Element]

Andrew – Heavens! No-one has described me as professional since about 1998. As regards the test result – no idea, not without a heck of a lot more detail. It’s possible that it was caused by something in the water; though equally likely it is something to do with the reagent – like not shaking the bottle enough prior to the test. Indicators can be surly.

I’ve come across automatic chlorinators – a friend of ours uses this system and he is very pleased with it. Certainly if one is using trichloroisocyanuric acid as chlorine source (which is almost always the case) then automatic monitoring and addition would be preferable to minimise usage.

My preference for saline systems is threefold –

- They minimise the formation of chloramines in the pool water, those things that give the water it’s “chlorine” smell and can be particularly irritating to the eyes. These are still present with automatic chlorinators, but saline systems only contain trace amounts;

- They avoid over stabilisation due to build up of cyanuric acid, though this is significantly less of a problem with automatic systems;

- They reduce the need to keep noxious chemicals around the place. Plenty of people are careful, but many really don’t take the care labels seriously.

Chlorine production by electrolysis in saline systems is controllable. Some have automatic analysis and adjustment, others (ours for example) have to be adjusted manually and are monitored by testing pool water for residual chlorine in the pool water two or three times a week. 1ppm chlorine is a good target, I have found. pH adjustment is sometimes needed to counter alkalinity from urea build-up, but now I’ve got most of the calcium out of the water (we’re on hard water) I’ve switched to using hydrochloric acid for this as this is more compatible with the saline system and this keeps things even more stable.

Saline systems have their disadvantages – the need to heft around big bags of salt every spring for example. The electrolysis kit can be expensive, and if the pool is heated then the heat exchangers need to be made of titanium, which is also pricey.

Since taking an interest in pools (everybody needs a hobby) I’ve come across other systems based on active oxygen, ozone sterilisation, bromine (in place of chlorine), and silver salts. All have their pluses and minuses as far as I can see, but on balance I found the saline systems best and we’ve gone for them on both the pools we own. Just an opinion, mind.

Have a pleasant weekend, Jon

[Poolguy]

Hi Jon

Thought I come back to you on this one. Just as a matter of professional chit chat mind.

I am interested in your ideas about salination. Mostly I find people choose salt system because they don't like 'smelly chlorine pools'. It often doesn't occur that a salinated pool also uses chlorine in the same way to sanitise the water, only that its produced in a different way. I am grateful to you for making that point.

I am interested in your comment about 'chlorimines' as well. This is the degraded chlorine which might be found in salt as well as chlorinated pools albeit in different amounts. The cure for which is more chlorine - it is as you say responsible for the smell and for sore eyes, and other reactions.

However, the presents of cyanuric acid (stabiliser) I certainly would not be using it in a pool with a Controller as the rate of dose of chorine is small but continuous which kind of negate the usefulness of stabiliser. Unless for example you have lots of kids doing water bombs continually. I understand that the rate of burn off of Chorine would increase dramatically with oxygenation of the water. So for older people who just want to float around they wouldn't need any stabiliser. So we use Eau d Javel (sodium hypochloride 9%) and Sulphuric acid (3%) to balance ph.

I understand what you say about noxious chemicals and storage as these can be a worry. But the autochlorinator system has a lockable box which stores separately the 20 litre containers of each chemical. Also with this system you don't handle the chemicals, they are fed automatically so that should dispose of the problems and the risks I hope.

I like salt pools as well but I feel that after a swim I want a fresh water shower to wash off the salt before it dries on the skin (mine is a little dry). I understand also that the salinator needs a bit of help through the day if its really hot and there is a lot of activity in the pool. Have you found that it cannot keep up under server load? I'm also not at all happy with the increase in corrosion that happens to any metal all around the salinated pool. Structures such as security fences are dear enough without adding corrosion problems.

Anyway, just a few thoughts for the pot.

Andrew