It definitely is possible to gas out your fish with DIY in a 10g. I killed several OTOs and two small "rubberlip plecos" a month ago to this.
I was using a 1 gallon bottle (2/3 full) and using the Champagne yeast recipe. After day two, I noticed my fish not acting right. The catfish-- which are accustomed to swift flowing, high oxygen water--- had died.
I was using my Rena Filstar XP3 as my CO2 reactor.
Just too much. I'm down to a 2L soda bottle and slightly less supercharged formula.