Used IO for a bazzillion years and will keep on. I have not measured the alk lately in a new mix but it was usually high...................................however I never found it effected my tank on a water change.

Except way back when I was on well water and no DI on my ro left my well water with a high alk and that combined with the high alk in IO at the time.....was hard on my tank. My stupidity never figured that out and cost me my 10yr old 2 ft sq. bubble coral that my clowns lived in.

What does Tropic Marin say about this. 39ppm would be unusable, no? I'd like to switch to TMP Pro, as I started Zeovit on one tank, but lack of stabililty scares me off.