The tank looks nice, what did you use to check it for leaks? I used to build huge tanks and tig weld them, 5 gallon to 400 gallon, stainless steel. Then I was taught on my first one that i thought looked great. I first was told to fill it with water, awsome I said, see no leaks. Then they said drain it and fill it with acetone or alcohol. Well I did and it had about 20 leaks, so I drained it ran a fan flow through it all night and fixed my leaks the next day. So I would not paint it until you check it.