Drained my concrete fish tank after a week of conditioning. Waterproofing using canvas and sealant not that good. Its OK for short term but for long term I don't think I can rely on it.
Upon close inspection found sealant peeling off, exposing canvas. Long term with fish inside I am worried it may fail. I decided to rip off all canvas and sealant, tomorrow I will use cement to sealed the panels "Temporarily".
As long I know where to "break" the concrete to get to the panels I guess it OK, from experience that access panel is use only maybe once in 20 years.
OK, then I will break the tank floor once every 20 years.