I remember my first years on BeBe. I seemed to do many things the hard way and some things the wrong way. It was a difficult and sometimes costly learning period. I am sure that everyone will join me in wishing you well with your 54.
To gain access to all 3 inspection ports on your A-54 is a very difficult task. Especially removing underseat refrigerator/freezer that I believe I see in the photo.
The three inspection ports for the 3 sections of the tank are:
Under the forward-facing refrigerator
Under the underseat refrigerator/freezer
Under the floor in the galley (shown in photo below).
If I were you, I would chemically clean/disinfect the freshwater tank via one of the ports...the easy one...the one under the floor.
1. To the freshwater water tank, add 2 liters of "household bleach" which is typically either 5.25 percent (“regular strength”) Chlorine
2. Fill the water tank with freshwater.
3. Allow the tank water with Chlorine to stand for 24-72 hours
4. Pump all of the water out of the freshwater tank using a submersible water pump through the middle inspection port.
5. Fill and pump-out 2 more times.
6. The appearance of the center patrician will mirror the other two.
CW Bill Rouse
720 Winnie St
Galveston Island, TX 77550
+1(832) 380-4970 (If I do not have your number in My Contacts, you will go to VoiceMail. Text me in advance with your number and I'll white list it.)