Water parameters for a reef tank.... can be .?

Jonathan blackwood · Mar 10, 2016

If I am running my skimmer 24/7, doing weekly 15-20% water changes, running carbon and purigen, and phosphate remove and all the basic normal required maintenance. .. will that be sufficient to maintain stable parameters to keep all kinds of coral ? Meaning I don't dose or add anything. I am running AI vega (×2) and have plenty of flow. And all the mention above is in my sump obviously.

Randy Holmes-Farley · Mar 10, 2016

Likely not. Alkalinity, and calcium won't be maintained by water changes alone in a tank with substantial growing hard corals or coralline algae. Calcium will deplete more slowly, and a few salt mixes start with so much that water changes may hold off the need for dosing for quite some time.

I show here that water changes would need to be 30-50% daily to maintain alk in a low to medium demand tank:

Water Changes in Reef Aquaria by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2005-10/rhf/index.php

from it:
Figure 23. Alkalinity as a function of time when performing very large daily water changes of 0% (no changes), 5%, 10%, 15% and 30% of the total volume EACH DAY. In this example, alkalinity is present at 4 meq/L (11 dKH) at the start and is depleted at a low rate of 0.2 meq/L per day.

Dizzirn95 · Jul 9, 2017

What if my Alk is high?

Ashish Patel · Jul 9, 2017

Water changes to me are good for replenishing trace elements. On a newer tank I rather not perform too many water changes - When a tank becomes overstocked with corals it becomes increasingly crucial to make large or more frequent water changes b/c they will absorb the elements we don't measure fast! With that said you will need to Dose Alk and CA - 2 major elements to keep a Reef aquarium... Even in a new tank like mine I still dose 6ML each of Alk and CA daily. Water changes are important but don't over do it!