Larry, I like your idea of using pool material, but it will have to wait until one of my pools breaks.
I'm very impressed with their durability so far.
I'm on Vancouver Island & they stay out all year & half full over winter.
I have 4 small swimming pools as rain water storage.
They are cheap plastic 10ft x 30" things that cost about C$200 & hold about 5000 liters each.
My first one was assembled in Feb 2020 & is holding up very well.
I cover them with black plastic tarps to keep debris & mosquitos out & reduce algae growth.
The problem is that the tarps break down & shed plastic into my water & the environment.
Does anyone have any suggestions for what material is either natural or wont break down, that I could use to cover the talnks ?
Thanks
I highly recommend the book "water storage" by Art Ludwig.
It gives a broad overview of the options & methods, then focus on Ferrocement.
I have built 5 tanks of 35,000 to 65,000 liters from this book.
But all of mine have been above ground.
