I was in a similar situation. I bought a used tank with a broken center brace. I had a canopy. which helped a bit. Eventually, I noticed the bowing. When I looked at the corners of the trim, I noticed that the water pressure was stressing the joints to the point where the plastic trim had cracked. I removed the top trim in its entirety and replaced it with a new trim piece. The replacement trim cost me about $15.
Freedom is the sure possession of those alone who have the courage to defend it. -Pericles
Let every nation know, whether it wishes us well or ill, that we shall pay any price, bear any burden, meet any hardship, support any friend, oppose any foe to assure the survival and the success of Liberty -JFK