My 2 cents worth ... I've tried multiple methods to raise pH (Kalk, Refugium, CO2 Scrubbers), but my favorite is a CO2 scrubber. This is my current design, which maximizes intake airflow through the bottom and pulls it out through a tube at the top (https://olliesshop.smugmug.com/40-gallon-Reef-Tank/CO2-Scrubber/). My experience has been it raises my pH about 0.3-0.4, from about ~7.9 to ~8.3, with it peaking about 8.4 during the day. Also, I currently don't run a refugium or Kalk. I purchase my Sodalime in bulk from Airgas, 16 bags at a time and each bag last about about 6 weeks.
I hope this helps.
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This is brilliant. I gotta try it. Was thinking of making something more complex but saw this and....




