Years ago I routinely used HC110 for prints, but I added some carbonate. I used the 1+31 dilution and added about 1 tablespoon of washing soda per liter. The actual amount of carbonate is not very critical. I don't know what they are selling for washing soda these days. I haven't seen it in my local stores recently. A somewhat smaller amount of pH Plus or anhydrous carbonate will work. The carbonate helps to produce true black where it belongs in about 2 minutes.