Long term Marco rock users

mjw011689 · Jun 14, 2022

Looking for some input from people who have used Marco rocks long term. I know there’s always the back and forth debates about whether it causes issues or not, and everything I’ve seen has been debated by people who’ve only had it for 2-6 months. I’m more interested in hearing what some one has experienced after a couple years in. Any changes? And has anyone had it long enough to completely purple up? I have not seen any of that.

how is coral growth on these?

Photos of some long term growth would be greatly appreciated.

blaxsun · Jun 14, 2022

I've had my Marco rock now since January 2020 (so not quite 2.5 years), and haven't had any issues. It's definitely purple - new rock usually gets covered in coralline within 30-45 days of adding. Corals grow just fine on it without any perceived problem.

A_Blind_Reefer · Jun 14, 2022

I’m about three years into a new tank with Marco. There’s a lot of conflicting info out there, ie. they suck up phosphate vs they leach phosphate, they leach magnesium, sps won’t grow. My experience, so take that for what it’s worth, is that they will soak up phosphates for a very, very long time in a bare bottom tank. I’m still dosing phosphate daily (3 years now, which I do not believe to be the norm. More like 1-2 years from what I’ve heard) to maintain 0.05 phosphate. Nitrates were an issue as well, but I think that had more to do with being bare bottom. I had to dose nitrate daily for about a year, and now just on occasion (once a month or so to maintain 5ppm nitrate). Everything else has been fine as far as coral and algae. Mines not purple, but that’s as the urchins gobble up all the coraline. I’m guessing that those that had trouble with sps were bottomed out and the corals were starving, but what do I know?

edit.. that said, I would never start a bare bottom, dry rock tank again. I forgot to mention all the bacterial issues and extended ugly phase involved.

fish farmer · Jun 14, 2022

Here you go.

First pic is from 2011, mix of fresh dry Marco, Florida Aquacultured at 9 years, Haitian at 6 years and some Fiji up to 11 years. Surprisingly everything looked clean at the recent setup, but GHA really got away from me for a few years.

This is recent pic of left side, the marco is covered with life, maybe not completely encrusted with coralline like my old Fiji pieces. Most of the live rock is from 2000 to 2005, one new piece of marco on the bottom is starting to get come coralline as well as mushrooms. hoping to put an encrusting coral there soon.