Plenty of people use the Rubbermaid containers or Brute 44 gallon trash cans. Rubbermaid stock tanks make great frat tanks, temporary holding, and sumps. 50, 100, 150, and 300 gallons. Durable and long lasting.
I use one as part of my sump. works good just don't fill more then 3/4 it will bow out on you over time. Mine only stays 1/2 full so it works great for me
I’ used a 27g HDX tote for a while. It was only a temporary setup but I don’t see why it wouldn’t work for a longer period. They’re so cheap if you’re worried about bowing you could double them up. I had mine about 4” from the surface and only had minimal bowing.
The sump on my frag tank is one of those plactic totes. As mentioned, just make sure it's food grade and safe. All the containers have a stamp with a digit. Each digit represents what the material is made of.
Here is one link to use, you can do more google searches if you want to help with your decision.
Diggin this one up- was just looking at the HDX totes at Home Depot for holding during a tank upgrade- none of the bigger ones had a plastic type stamp on them. The 15g ones had a 5 PP stamp but the plastic seemed to be a bit different. Looked at their website and they are listed as polypropylene however I’ll note in the Q&A section I found this comment about its safety-
“No absolutely not RODI water stored in my 27 gallon tote measures a tds of over 900 after a week of storage. No idea what is leeching out.”
I’ll take that with a grain of salt, but I have PTSD from tin issues so I’m pretty paranoid and careful about what I use.