Hi everyone

I am looking into getting a figure 8 puffer, and not sure which tank to get. A 25 gallon or 35. The last time I had a big tank our water bill went through the roof! So my husband is not keen on the bigger.
25 gallon with puffer alone = 50% water change or ?
25 gallon with puffer and 3 bumblebee gobies not doable?
35 gallon with puffer alone = can I get away with 25%?
35 gallon with puffer and gobies x 5?
help
