I'm new to the forum and would like an opinion from some of you experienced pool maintenance guys.
At the end of last year I bought a house that came with an above ground pool. When I opened and started using it in May, I put into the filter tank a filter cartridge that the previous owner left for me. After a week or so I took the cartridge out to clean it, because there was green algae on the bottom of the pool (after 2x pool shock). To my surprise the bottom cap of the cartridge was cracked in a few places. I thought that it was a dud, so I ordered a new one. Well, after 3 weeks I took the new one out, and it was also cracked in 5 places. Do you know what could be causing the cracks?