buckdendave

Thanks - I'll give it a try when next there. Dave

The problem is that the liners are made from plasticised PVC, i.e. PVC polymer with a compatible oily liquid that makes it soft and pliable, but is not easily extracted.  The plasticiser is compatible with the oil in suncream, and that has colourants added to it.  So, as oil floats on water there is a concentration at the water line.  Once its migrated into the PVC there is no way its all coming out.  All I can think of, to minimise the consequences, is to lower the water level and carefully clean around the stain line with a mild detergent, then rinse off with clean water - all the time keeping any detergent out of the pool.  I have a GRP pool and get the same orange brown line, but so far it has always cleaned off.  However I have my problems too - earlier this year I moved the pool pump, filter, etc., from a horrible box in the ground into a pool house and had to cut the pipes so I could extend them.  All OK except sealing off the pool return - in the end I covered the cap in the pool with some thick PVC and held in place with a stainless steel jubilee clip.  Marvellous, it worked a treat, no leaks.  But a couple of months later when all the pool pump works, etc. were done, I removed the pool cover to remove the PVC and jubilee clip and found a brown iron stain up the side of the pool - not all the stainless clip was what it was supposed to be (not that stainless is completely anyway).  But how to get rid of the brown stain?  A lot of gentle rubbing with plastic pan scourers (using my feet!) has reduced it hugely, but what I'd really like to do is try a mild solution of oxalic acid on it - can't drain the pool though and don't want to risk contaminating the water, so I'll live with it. Dave          

The bubble covers are made from polyethylene.  Very difficult to bond with adhesive unless pretreated (not really a practical proposition at home).  A fusion weld is effective - but is rather tricky to do.  You might have success with something like the edge of an iron with a PTFE coated base.  Melting point of PE is around 130C but you need rather more than this for a fusion weld.  Practice on an offcut first. The cheap plastic tarpaulin type covers are usually made from oriented PP or possibly HDPE that are woven and tack welded together, then sewn around the edge.  Same problems regarding adhesives, except that the surface texture will lend more mechanical grip (but I wouldn't rely on it). UV resistance of polyolefins (PE and PP) is not particularly good, especially if thin and made from transluscent or transparent material.  UV stabilisers are added to give some protection but will not last more than a few years.  Using a cheap plastic tarpaulin cover on the rolled up bubble cover when not on the pool is a must as far as I am concerned.  Never pay extra for a bubble cover with a Roman end or whatever (not if your handy with a pair of scissors anyway) as they are so easy to cut to shape yourself. Dave      

That'll be Cite 2. Dave

Completely bonkers!  A publicity stunt, no doubt. Dave

We bought a couple of mattresses from Ikea at Toulouse via the website (in English), and had them delivered.  All worked OK. There was (and probably still is) a shop/warehouse selling mattresses and beds at the commercial centre on the East side of Carcassonne (sorry forgotten the locality, but its near the other Geant hypermarket from the one at La Bouriette), down a side road near the Pagoda.   Dave

Richard You're right.  I always use caustic soda anyway. Dave

There are a huge range of colours available.  See www.prb.fr for one of the makers websites.  I am no expert on crepi, but am fairly certain that the pigments used will be permanent mineral based types that fade or change very little on weathering.  If you go mixing in acrylic colours or anything else you won't know what you're adding and the lightfastness may not be up to snuff, so you would almost certainly get shading.  The weathering resistance of pigments varies hugely between types and the media they are used in. Dave

You pour the hydrochloric acid (sold by the 5litre from the hypermarche) straight into the pool (not too much, a litre or two will have a noticeable effect).  Or if you prefer, pour into a bucket of water first and then add that.  Always add acid to water and not the other way round, or it can heat rapidly and spit back at you.  No clogging or any other negative other than the safety issue below.  [Sulphuric acid - same rules apply, but really its inferior to hydrochloric]  To raise the pH either use bicarbonate of soda or caustic soda (usually in 500g or 1kg tubs).  With this latter always add the soda to water and not the other way round.  Try 100g.  Mix in a bucket and add to the pool. Run the pump to ensure mixing. I should point out that hydrochloric acid and caustic soda need to be handled with great care as they are extremely corrosive or caustic and can cause a serious injury on the skin.  In addition hydrochloric has acidic fumes, so avoid breathing them.  Rubber gloves and goggles are the order of the day.  In any case rinse with lashings of water afterwards.  Never mix them either as you will get an explosion or near to it.  And store in safe place where nobody can get at them.  This isn't over the top, it's essential. Dave

Absolutely agree with your synopsis.  Obviously without knowing exactly what it's made of I can only guess, but in any case any such repair, if it works at all, is likely to be temporary.  Something like epoxy resin (not the 5min stuff) may work for a while but it could fall out again at any time.  However if the pump body were to be make of something like PVCU or ABS (which seems unlikely as the ones I have seen have appeared to be glass reinforced PA as well) you might bodge it with solvent cement.  Try a bit on the base and see if it has any effect. Dave      

Oh come off it teapot, I did say a "regular pool professional", and I am sure you know what I mean.  Most of these guys are pretty good at solving the usual problems, but don't kid me that most of them know any chemistry outside of their narrow field of experience, because they don't.  I have been watching comments on this subject on the forum for a year or two and I know that almost by instinct these guys know the right solutions (far better than I, by the way), but frequently I have seen attempted explanations of the chemistry behind it and they haven't been right (you aren't one of them).  Actually this doesn't matter because even if the explanation isn't right the problem has been fixed.  More power to their elbow.  Getting it wrong can have consequences, and chlorine is not exactlly benign, but follow some basic rules and all will be well.  Some things you can't mess around with, and ClO2 is one of them.  Yes people can make a damn good living by learning a trade and not getting a University degree and sometimes I ask myself why people bother, but don't tell me the world can manage without them.  Try going to witch doctor with a heart complaint.  I don't think so.       Dave

Yes ClO2 would be very good if it weren't for the side effects, but you wouldn't let the stuff be used by a regular pool professional because they just don't have the chemistry knowledge and it's too darn dangerous if used incorrectly.  The concentration we use is only a few ppm.  We use a temp of 40C in order to get a rapid effect, and it takes a few weeks to demolish an EPDM O ring, for example.  We will be doing more work at lower concentrations and temp but it'll take some time to work through the programme.  You don't work with ClO2 without taking a lot of precautions and controls to constantly monitor and adjust concentration and pH.  For safety reasons the generation kit is in a concrete blockhouse outside the lab and its piped in solution through the wall to the loop. Dave  

Generally correct but the safety of chlorite is a matter of some debate I think (in drinking water). I thought about its potential use in pools through adding sodium chlorite, but haven't taken that step, and wouldn't recommend it. The trouble with ClO2 is that it such a powerful oxidising agent that it has the ability to be destructive - for the same kind of reason that its so effective at dismantling pathogens.  We have been doing a lot of work with it in our test loops and it has the ability to destroy the loops at any significant level, especially as temperature rises.  You can be sure that any gaskets or seals are going to be attacked PDQ, for example.  Everything has to be fluoropolymer based if its going to last.  (Yes I'm a polymer chemist) Dave     

Richard. I'm impressed - I know a bit of chemistry and can just about follow some of your messages.  How you've got the time I don't know. However, just to add something else to the pot.  Some French Water Cos, especially in the South, but also in isolated places elsewhere, are not using Chlorine or Chloramines as the sanitiser, they are using Chlorine Dioxide.  It's fairly commonplace.  Maybe you know this? They do it because it is extremely effective at low dose levels and doesn't form chloramines - therefore the quality of water (taste) is considerably better - it really does make a big difference.  Of course there are a few drawbacks - one is that instead of chloramines you get other things that may be no more healthy.  And it is, of course a very powerful oxidising agent which can be quite destructive. What happens in pool water, you can probably predict better than I. Dave    

Because it sometimes starts and on other occasions doesn't, I think it's more likely to be the starter solenoid than anything else, though the battery connections are also worth checking.  When you turn the ignition key, which is a low current device, it activates the starter solenoid which passes the much higher current required by the starter motor.  It could also be the ignition switch.  An auto electrician can easily check. Dave