why not just use a black light to see when your pulls/cooks are finished pulling goodies? U can see relative concentrations too.. Many cooks of 30 mins with slightly vit c acidified water or plain filtered water (check ph is 7 or just below..) me thinks will be key ro removing all with energy efficiency, using the light periodically to see when ur wasting ur time. Then cooks combined and a dash of vit c added to act as anti-oxidant and reduced.
A cat i knew used to get reliably 15+ % harmalas from rue like this in extracts. You'd be suprised, the goodies just keep on coming out when U looking with uv, 7 cooks was not enough sometimes, sometimes 10 or 11 haha till he got bored (was in past so if memory serves correct). Mayb your cook times seems to make such a huge difference to your brews because you're not using acid and your spring water is slightly alkaline as most mineral/spring water is in my experience. You are having to wait for the now freebased harmalas (from the basic spring water) to react with co2 in the air under a sorta reflux for the formed carbonates to get into solution..It seems the conundrum lies in the fact that the harmala salts are not too water soluble but quite water soluble. So the water added to brew gets saturated quickly and the most likely naturally occuring carbonate needs more fresh water to pull more, and again, and again..
Mayb whats important is how many cooks not how long? It only gets dependent on how long U cook when your water is naturally slighty basic and you have to wait for the co2 in the air to acidify the solution or salt the freebases through cooking?
Use a blacklight, then yer not guessing, harmalas glow sooo bright haha. You'll see stains start glowing where you spilt a brew a year ago!