[Delphinus]

Thanks Doug. I'll test the reactor's Alk output, I have no idea what it's at, I've only measured pH of the effluent.

One thing catches my eye in what you just said - "good kalk mix." I'm wondering if part of my problem is I'm using Mrs Wages pickling lime (Someone gave me theirs when they left the hobby). I don't really like the stuff very much. It turns poo brown after a week although the pH is still 11ish so I think it's still working but nevertheless I'm wondering I should switch to a proper kalk mix.. I only use a few tablespoons per week or two so it takes me forever to use it up..