You def have a contamination of some kind. Have you tried following your cleaning steps as you do them normally, waiting for everything to dry. Then filling up all fluid contacted vessels, exchangers, and valves with some water. Measure the pH of the water before it goes in your vessels, and measure the pH of the water after it contacts everything. This is the only sure fire way to know. You can also measure the pH at individual steps as you go, measure after adding to the kettle, after circulating through the pump, after contact with whatever type of chiller you have. This way you can narrow down where to focus.
I have not tried to measure the pH of my water before and after it enters my kettles. In the meantime, should I try this on it's own since I will not be brewing for a bit?
It was suggested earlier in the thread that "you won't be able to get a reliable reading by itself" of distilled water (they were referring to my sparge water). But I imagine what you're suggesting would be to see how much of a difference there is once it contacts my kettle, pump and hoses.
I will attempt to measure pH at each step next chance I get, but just to share my process:
Note: I don't sanitize on the hotside, except for my chiller.
1. Strike water (distilled) goes in the mash tun the night before with sugar and yeast (to deoxidize the water)
2. Morning of, strike water is recirculated and heated up to strike temp. Minerals/salts and lactic acid are added after 100°F
3. Grain is added and mash steps are followed, including pH reading 10 minutes in. Since I batch sparge, my sparge (distilled with minerals/salts) is my mash out and recirculated for 10 minutes at 168°
4. Boil kettle is brought to boiling temps and runs for 60 or 90 minutes.
5. I use an immersion chiller, which I DO sanitize in Star San (even though it's going into the boil kettle at 211°). At flame out I add the chiller and recirculate/whirlpool while chilling.
6. Stainless steel fermenter is sanitized---all interior surfaces covered and drained from the bottom. Wort is added to fermenter. Post boil pH is taken.
Once the beer is in the fermenter:
1. Mash tun is rinsed (grain is removed during the boil) and I use tap water to fill about 5 gallons. I add Alkaline brewery wash and recirculate for 30 minutes @ 150°F. I scrub the sides that aren't touched by the cleaner, or try to aim my return arm at the walls above the cleaner.
2. Wash is then transferred to the boil kettle and also recirculated for 30 minutes @ 150°.
3. (Old method) Cold water rinse the mash tun with tap water. Cold water rinse the boil kettle with tap water
4. (Old method) Pump, hoses and RIMS were hand rinsed
This process has slightly changed. Since my first post (Kolsch), it was recommended to use hot water rinse instead of cold water rinse, so I've switched to that. And since the second beer with high pH (Saison), I stopped hand rinsing the cleaner and started recirculated clean water through the system after using alkaline wash. The clean water is recirculated for 10-15 minutes at 150°F in both vessels.
The new clean water recirculation was not used pre-Saison and I incorporated it after that brew day. To be safe, the day after brewing, I ran another cleaning session and recirculated the brewery wash (slightly weaker blend) for 60 minutes in each kettle @ 150°. Then ran water @ 150° for 30 minutes in each kettle.