Originally Posted by Miller
I m gonna replace the smaller reserve tank with a plastic one...There is a load of space where it sits that is going to waste so its only sensible that i utilize it for max benefit.
As long as there are no major problems with using a plastic tank
This is one of those problems that can pose multiple answers that are right and wrong and flawed. Almosy every angle has been covered in the replies: mend what you have, use ali, use plastic...
Personally, seems to you have two tanks that, presumably, have given good service until now. One of them now has an easily repaired fault if done professionally.
All other options potentially involve pandoras box ( sorry Pandora, no offense) and additional expense by modifying the engineering of the installation.
Make sure you don't throw the baby out with the bathwater