Swimming pool chat


Perhaps someone could start a separate thread with my topic?

The problem lies with the installer of the kit not really knowing what he was doing. They then found someone who installed and sold these items of control who came round, re-wired the bits the installer had got wrong and things worked for a while. Now, at the end of last season, it stopped working and I need someone to come here and give me a tutorial in how it all works and to find out why, at the last call, it did not.

The installer has been asked for the contact details of the person who knew what they were doing but seem unable to find them!

Many thanks John, I will follow your advice.

Just a theory which, if you agree, may help others as well...

When setting up the pool previously, I have ensured that the chlorine and PH levels are correct, the water clear etc. before departing for the UK. I have achieved this through regular checks with test strips.

A correct reading for chlorine on a test strip does not reveal the underlying situation with CYA/free chlorine. Therefore I am misled into thinking that everything is OK, when in fact the chlorine is there but locked up and unable to do it's work. With the ColorQ I can determine the CYA level and consequently add non stabilised Chlorine (Javel?) to unlock the chlorines sanitising effect.

Also save my money on winteriser and just ensure that the pool is strongly sanitised before turning off the filtration and installing the cover?

The issue is that the two pumps do not seem to wish to come on and I do not seem t be able to programme the unit so I need someone to tell me how to do it.

Put it down to old age and preferring something with a handle!

Chris, what's the issue with your dosing unit?

Paul, yes it is always the best policy to add a dose of chlorine before removing the cover. If the water is at zero sanitiser and in anyway nutrient rich algae can grow but unseen, we call it nascent algae, removing the cover lets the sunlight in and just like any other plant it can bloom in hours to a nasty green.

As to whether use use "choc" or javel should depend on the cyanuric acid level (CYA/CNA) if that is 30-50ppm then use javel, if it has dropped over winter the a bit of choc will add some more cyanuric acid stabiliser. You don't need to buy choc as the formulation is the same as the large gallets they are just smaller so they dissolve quicker, breaking up a large gallet into small parts will achieve the same thing. Choc is a process not a product.

Anti algae will not stop an algae bloom, it's not strong enough but anti algae can cause foaming on the water and more chlorine is used to burn out the anti algae so less is available to actually fight the algae attack. It's just the pool industry selling more products. Winteriser is exactly the same formulation just labelled winteriser to increase sales in the autumn when otherwise they wouldn't be selling any. Chlorine will kill algae quicker than anything else so best to use that but chlorine gets used up doing that so needs frequent dosing to replenish.

Hi John

many thanks for your previous advice, much appreciated.

I recently did a ColorQ test on the (Desy)pool water (It is still in Winter mode with the cover on and was treated with winteriser in October) The chlorine level was zero. Having suffered serious algae problems during the last 2 years, before I tuned in to your advice, I am determined to do better this year!

Shall I add some diluted choc or javel now (before removing the cover and starting the pump) to up the chlorine level and start off on the right foot this year?

For info the pool was no problem for the first 13 years of operation, with 1 new liner and 1 new pump 3 and 5 years ago respectively. For the past 2 years I have set up the pool in early May with all the levels corrected before returning to UK leaving our long standing pool maintenance man in charge. He has then called me a month later to say that the algae is out of control, despite several gallons of anti algae being poured into the pool. Last year I went over with my recently purchased ColorQ, changed the water completely, and made sure that all the levels were correct. There were no more problems last year. I had been assured that the ch and ph levels had been maintained correctly.

i am anxious to avoid the problem for the third year running??



I am looking for someone who can help me with a CTX Guardian 2 pool control which also has 2CTX class series metering pumps (one for Chlor and one for PH) please.

Does anyone know of someone with whom they can put me in touch please?

Yes I can but for forum rules it maybe better to PM me. BTW the low loss of chlorine was still good.

Thanks John, brilliantly clear answer as always. I'll look for a better test kit, can you recommend?

Hi Martin.

OTO you are referring to the chlorine content?

The fresh water is pretty clean and that would have been a shock dose, with nothing in the water plus covered and winter temp then the chlorine level can stay up but, and you knew there would be. OTO measures total chlorine and not the free chlorine so what you really have is a measurement of the loss or degradation of chlorine and not the active sanitiser level.

Yes a better method of testing for free chlorine is also needed, preferably by a DPD1 method (DPD1 is a shortened name for the chemical used to test free chlorine)

Hi John, My apologies is this has come up before but I think it is quite strange. Put in a new liner pool in the Autumn and filled it with tap water (don't trust the well water yet). When tested with an OTO test kit it come out as 7.3 - before I put anything else in. I left it like this over the winter sans pump under the winter cover with a drain for excess rain water. I've just tested the water again and it's still says 7.0. The pool water is absolutely crystal clear. Is French tap water that dosed or should I buy a better tester?

Hi Tracy, not that I am doubting you although I may doubt the Aquachek especially if they have been open for a while or not stored in perfect conditions but pH at 6.2? That would make the water aggressive enough to attack any source of metal from pool ladders to the screws securing fittings like skimmers and returns which would turn the water coloured quite quickly. Can you re check, preferably from another testing source, begged borrowed but not stolen!

Is it a liner pool?

For total chlorine you need a DPD3 tester or preferably upgrade to a photometer tester if funds allow.

Cyanuric acid is a chlorine stabiliser added to most pool products to protect the chlorine from being burned up too quickly by the sun.

Hi John

Free chlorine 4.1, PH 6.2 and alkalinity 82. I have an AquaChek which was left by previous owner, how do I find out total chlorine? I don't have test for calcium but there is very little deposit around water edge. What is cyanuric acid?

The water is now a greeny-yellow.

Regards Tracy

Hi John,

Will do tests and send results.

Water comes from a well and I had just topped the pool up.


Hi Tracy,

That isn't a lot of chlorine, it maybe more than you usually run at but it's not that high. Never the less the water going yellow sounds like the chlorine has reacted with something in the water, possibly metals like iron.

Could yo post a full set of water test results with Free & total chlorine, pH, alkalinity, calcium hardness and cyanuric acid levels. Where does your water for the pool come from, the tap or a well?

HELP!!! I put too much Chlorine Shock in my pool and the water has turned yellow. What do I do? The reading was 6.7 yesterday but this morning it's down to 5.2.

Novice pool owner Tracy

Desy = Desjoyaux

So you don't have a chlorinator but the advice is the same vinyl pools can and do run better with lower alkalinity, it's only there to buffer the pH but is really shown too high on most pool information just in case someone has a tiled/plaster pool and half reads the information as it is required in tile/plaster pools to protect the surface from erosion. Of course one could argue the industry likes people to run with the higher level as they then purchase more pH- to bring down the pH each time it drifts up.

Yes there are products to increase Alkalinity and that is done with bicarbonate of soda, or Alk + as most pool stores label it.

Hardness is increased with calcium chloride, don't ask for that in a pool shop their heads will spin usually called H+.

To lower alkalinity you add pH- to reduce the alkalinity and pH to around 6.5-6.8 and then aerate the pool water to raise the pH back up but leaving the alkalinity lower as that won't be affected. That may need several goes to achieve the end result.

Reducing hardness is best done by replacing water with a lower hardness, I can do it another way but that is specialised work.

Thanks John, I'm certainly much the wiser on pool maintenance thanks to your advice.

'Being a desy'...???

The pool is sanitised by chlorine only, not salt. Are there products on the market to alter the alkalinity and cacium hardness levels if future tests reveal that I need to?

Best regards, Paul

Thanks John

Our pool is located near Riberac in Dordogneshire.The local water is hard, but not too bad. The pool is a Desjoyaux liner pool, with the filtration by a bag in the pump housing. The pool is 10m x 5m with a roman steps end. 1.2m deep throughout.

Last week whilst in residence , I carried out daily ColorQ tests to see how the water quality evolved over the week, and all was good with CYA averaging around 40 to 42. The Alkalinity and hardness were quite low, so I was just wondering if this needed attention?

Best regards, Paul

Hi Paul,

Not too specific quite low, with a vinyl pool alkalinity is not so important and with you being in a hardish water area you can afford to allow an alkalinity of around 50-60ppm. It really depends on your pH and how stable that is. Being a Desy, I am guessing it's a salt chlorinator which by nature have an upward drift in pH so it climbs towards the higher numbers. If you do the ideal then you will have to watch your pH much more carefully as high pH means less effective sanitation from the chlorine. On my pool I wound the alkalinity dowm to 38ppm at which point I began to get a gradual fall in pH towards the lower numbers so I brought that back up to 50ppm as I like a nice stable pH at 7.2-7.4 without too much pH- being used.

Hope that helps


Thanks for the credit Paul and welcome to SFN.

Do all products contain CYA stabiliser, No, The unstabilised versions are Calcium hypochlorite and of course liquid javel as choc is a process and not a product just because the industry labels it like one.

To check the packaging label is the best way of determining what you are purchasing, stabilised versions will say The formula is Tri chlorinated isocyanurates (trichlor) or Di chlorinated isocyanurates (Di chlor) or a French anagram of the same.

To answer your water questions I need to know more about your pool construction liner or tiled/plaster and a bit more about the water you use for the top ups and it's levels. The biggest issue with the "ideal" levels is they are not pool type specific and your water will find it's own level based loosely on the water in your area so more information needed.

Regarding the ColorQ, also available in Europe with the warranty for 2 years which US models won't have. Really must get my website finished!