Mines was growing pretty fast. I do recommend a bigger tank and it shouldn’t become overwhelmed. For me Rango started glass surfing a lot because he didn’t have enough room in the 40 once he got to 18”. The cheapest 120g new tank I found was on Dubia.com and next was Wayfair which is where I was going to purchase mines. However. I started thinking about building one which you can do for under $100 and there are videos on YouTube. Other options I recommend is Facebook marketplace and Craigslist. Ultimately, I chose to build one from furniture so I started looking at dressers, buffet tables, and tv stands that had at least the 120 gallon dimensions of 48x24x24 on Facebook marketplace. I ended up finding a tv stand with dimensions a lil bit bigger than 120 and purchased it for under $75 (There is a pic of the final result on my profile). All we did was cut out holes to accommodate the lighting to be mounted inside. There are videos on YouTube as well about turning furniture into a tank.