Hey Guys! I just joined this forum, but i thought i'd add a little bit of advince.
In the wild, chocolate gouramis do live in blackwater with a pH of around 4.0-6.0, but most of the ones that you see in pet stores are tank bred, so they are much more adjusted to a higher pH.
A constant pH is much safer and better for the fish than constantly trying to lower it, which causes unnecisary stress. I have 10 chocolate gouramis in a 15 gallon with a pH of 7.4 and they are very active and healthy. The most important things are:

-temperature (chocolate gouramis need a temperature between 80-86. Around 84 is best, but the temperature must remain constant.no fluctuations)

-the type of water (i use peat filtered water along with blackwater extract.this adds necissary nutrients to the water and help to maintain a stable pH)

-water cleanliness(chocolate gouramis need EXTREMELY clean water. a water change twice a week is usually the best route, but once a week won't kill them)

-tank companions(chocolate gouramis do best in species only tanks or if need be, with other slow moving, non aggressive fish. They should be kept in groups of at least 6 or else they will feel insecure and probably won't eat)

-type of food(some will only eat live food, and they would rather starve than except dead stuff, however most can eventually be weaned onto frozen or flake food. If feeding flake food, make sure that it is crumbled into VERY small peices as their mouths are extremely small. I feed mine flake food in the morning, and frozen food at night. They absolutely love frozen bloodworms)

I hope this helps you guys. I have been keeping chocolate gouramis for years, and if my mistakes can help you guys so that you don't make the same ones....then they were worth it.
Have a good one guys!!