In the ATM 49 package there should be part 1 and part 2 wrapped by a sheet with instructions, follow the steps and You should be good to go.
IMHO, the safest route is to use distilled water, so that You will always have same results. Tap water is hit or miss, even when filtered.
Studional was available back in the old Agfa times.. Now, You can rely on ADOLUX ADX A+B - for me it works the same, if not better.
Good luck and have fun in the darkroom!
ATM 49 gives very retro look
In Bremen, Germany the water is generally soft or very soft. Nevertheless, I will try with dist wasser.
Now, I have lots of questions running in my mind. I really don't know which film is best suited for this developer. I was shooting HP5+ and gave it to the lab and results were really terrible.
I am thinking to get my-selft ADOX CHS 100 ART or slower one or film with slight contrast.
Suggestions are welcome.
ATM 49 is kind of equalizing/balancing developer, so its generally accepted that it works best with high contrast scenes or slow films (~20-50ASA) - to keep detail in highlights and shadows.
I have used it mostly with european films in the range of 20 to 100 ASA and its excellent.
Could not say anything broad in connection with Ilford or Kodak films - I have shot mostly Kodak Technical Pan, developed in Rodinal and its great but that about it.