I use a home-made ato, just a tom-lifter pump and a float valve, cost like $20 and super easy to make. I keep my topoff water in a 5.5g tank inside the stand, works perfectly. I used the stock skimmer for a while and it worked pretty well, just a tad bit noisy. I eventually upgraded to a tunze nano skimmer when a good deal popped up. I don't understand what you mean by the compartments look bigger.