Millet Dark Beer

Recently I brewed a batch (15Liters) and ran out of Citric acid to adjust my water. So I used ascorbic acid and found that 2 tsp in 23liters did the trick to bring drop the pH of the water to 6.0 from the tap it was 8.0. I'm now waiting on the finish of my bulk aging and did a pH test 4days after pitching the yeast. The beer is somewhere between 5.5 and 6.0 currently and has a different smell that I'm used to. I have never used this acid before and now I'm wondering if anyone else might have stopped using it because of this?

Any thoughts or experiences you could share?

I did some quick searching and there are some threads that say ascorbic acid can result in off flavors in beer so maybe it is not a good choice.

I am no expert, but my understanding from "How to Brew" and "Water" (John Palmer) is that acid would be used primarily when the residual alkalinity of the source water was too high for brewing a pale beer. The dark roasted grain has the needed power to bring the mash pH down into the right range if the source water has high residual alkalinity so I would not expect you to have to add acid for mash water intended for a dark beer. Did you measure the mash pH? From what I have read, the pH of the mash is what is critical and that is affected most by the acidity of the mash and the ion concentrations in the mash water.

Do you have analysis results for your source water to know how much magnesium, calcium, SO4 etc. is in your water?

I tested the mash but I can't get a good reading as the mash is very thick. I might want to test the clear liquid after conversion to be able to see the change in color. The kit I'm using is for fish tank water as it was the cheapest one to use. The reason I was adding to the water is I would like to get the water down from 8.0pH tap water to brew a lager some day and the water is so Alkaline that the darker grain wasn't lowering it enough to hit 5.2-5.5pH.
Any other ideas you have tried? or acid you like to use?

My tap water is also very alkaline, and I have struggled with the same issues.

I now brew with a blend of 5 gal RO water (costs $1 to refil my jug), and 2 gal tap water.
There is nothing magic about this ratio, but I am hitting the right pH, and it is convienient that 5 gal water jugs are the norm.

I will try this next batch