There could be three issues with the pepper not setting fruit in a salsa garden: water, light and patience.
With water, start with an immediate rinse and refill. Remove all the water from the reservoir (a siphon works best for this, we sell a rinse and refill siphon that works well) and add new, fresh water and nutrients. You’ll see the plants look better (less leaf browning) within days. Even mix ½ and ½ with distilled water when you add fresh water back in.
Next, regarding light, peppers can tend to grow more slowly than tomatoes. This can mean that your peppers get shaded and don’t get enough light to set fruit. Look at how your plants are growing together, and then, if needed, do some gentle pruning to your tomatoes (don’t prune the branches that have fruit!) to get more light into your pepper plant. Finally, some of the lower leaves will turn brown just because they are not getting much light and aren’t needed by the plant. You can trim these lower leaves off without hurting your plant.
Finally, patience is key. Plants have minds of their own and will set fruit when they want to, even though we are offering them ideal conditions. That you are getting flowers is a good first step (a pepper plant will almost always have a lot more flowers than fruit) and if you pay attention to the first two variables we’ve covered, the fruit should start setting too.