[Umbrian]

I am afraid this is not strictly speaking a gardening question but does pertain to life in Mediterranean (and other hot climate areas) and so I am hoping the moderators will allow it and that perhaps one of our scientific brains will be able to answer it - David?
I have noticed in recent years that the waterline area of out pool's plastic liner is getting increasingly stained and discoloured after the grandchildren have been here smothered in sunblock cream. This year it is positively green which does not look at all good as it appears to be algae, also their swimming tunks and costume are getting stained green. I suppose with the increasing knowledge of what works well in these creams more constituents are being added. At first I thought it might be that the pool liner was getting less resistant as we have had the pool for 12 years now but the stains on the swimming costumes rather contradicts this. Our usual proprietry pool liner cleaner gets rid of the accumulation of grease but does not help much with the staining Any comments and any handy tips for keeping it at bay? (Don't say drown the grandchildren even if at times I feel like it!)

[David Bracey]

Not very scientific but we used to clean our liner with a squirt of detergent or something like Ajax and a strong scrubbing brush.  Best is to  get kids to wear T-shirts in the pool and cut down on the sunblock.  I think the staining may stay ...depends on the amount of rubbing. Get the kids to do the work and then drown them.

[JTh]

I recommend green swimming trunks to match the liner.

[Umbrian]

Thanks Jorun and David - I think my problem is here to stay as daily cleaning seems to be having no effect, we have tried getting the kids to wear T shirts but with little effect.  Nice of you both to reply though

[MikeHardman]

In case it sneaks into the equation as an option...
I would say no to the decorative strips of liner you can add around the waterline area.
Yes, they can cover up discolouration and other issues, but they are not cheap, need to be installed well, provide crannies for grime to lodge, need redoing after a while, entail a risk of them starting to peel off prematurely if not stuck on well, and you cannot change them if you don't like them (or you would risk damage to the main liner, and would inevitably end up leaving a horrible pattern where it came off).

[Umbrian]

Hadn't really considered that option Mike but it sounds fraught with dangers!  Just have to keep the old elbow grease going and hope for the best Hopefully the grandkids will soon be able to take a little bit of sun .....I understand that it is actually beneficial in many ways but try telling over anxious parents that! Once it was  factor 30, now it is factor 50! I am not uncaring but wonder where this over protection (in many ways) will end. I grew up grubbing around in my grandmother's garden and have lived to tell the tale.

[MikeHardman]

Also, and I can't remember if I ever verified this, because of the high factor of today's sunscreen creams/oils, they are adding vitamin D to them - to make up for the shortfall caused by the screener!
It get's dafter and dafter!
Like you, I managed to survive despite playing in dirt, messing with chemicals, etc., etc.

[David Bracey]

Check the colour of the sun block. It may be green!

[ritamax]

Yes, it's awful with those sunblocks, but unfortunately necessary. It has been said, that the sun is more aggressive to us than before due to many factors, ozone zone and sun activity, climate change etc. The skin cancer rate has gone up something like 200%. I use a sunblock, which is recommended by all dermatologists in Switzerland as it contains only 2 filters: Anthelios +50 spray of Roche-Posay, very light, no perfume, absorbs very well and is very water-resistent. It is not cheap, but the bottle lasts very long.

[Umbrian]

No!