corrosion at pool edge

[rpats]

Hi

our in ground pool has a vinyl liner which appears to be held in place at the top by a strip of aluminium or similar. The pool surround cinsists of terracotta tiles which are cemented in place on top of this.

My problem is that in places the aluminium is pitted and corroding. Does anybody know what causes this and how to stop it? The corrosion seems to occur in random places rather than for example under joins between tiles.

The pool is covered in winter so I don't know if the corrosion is happening then or in summer.

Thanks in advance for any suggestions

Richard

 

[woodyp]

Do you have a SWG, and if so, what are your salt levels? Please post up a full set of test results and how they were obtained.

 

[rpats]

thanks for the quick response. No SWG,I am using chlorine tablets

I dont have an accurate test kit, just a "drop in a tablet and compare the colours" thing. I will see if I can find something better but I am in Italy so don't have access to products that you do in the US. But based on what I have, Chlorine levels and pH are low, I am in the process of raising them

 

[chem geek]

See if you can get the Palintest SP 315C. The only thing not in that test is that the chlorine test is DPD instead of FAS-DPD. Otherwise, it has everything you need and should be available in Italy.

 

[rpats]

Hi

I could not get the Palintest locally but got a different kit which uses droplets rather than tablets to add to the water. Shows my Cl is 2.0 and the pH is 6.8 so I am trying to get these within the normal range.

However I suspect this is a problem that has occurred over the winter when the pool was covered. Who knows what whatCl and pH were then. As we are not here all year round I get someone else to close the pool for me. I guess if he put too much Cl in prior to putting the cover on rhen the water would be acidic and could do this?

I asked at the local pool shop and they had never seen this problem

Any suggestions welcome

Thanks

 

[chem geek]

Yeah, he might have used Trichlor tabs which are acidic and if he didn't adjust the pH it could have gotten low and caused metal corrosion. However, if he just added some chlorine to start, then it's not as likely for the pH to have dropped very much.