This is interesting too.... when on TM Pro, I had coraline all over the glass, consistently scraping it, ever since switching to RC, a bit has remained on the rockwork but I get nothing on the glass whatsoever. Thus I assume not enough coraline to chew up the alk. I've heard some seed it, on a really old system worthwhile to try?My mostly softy tank chews up alk and calcium. I can think coraline for that. Just because one has a softy tank doesn't mean alk and calcium won't be an issue