AWC vs Dosing

[bgoldb]

Please help me calculate the water volume % I would have to change out each day in order to completely discontinue dosing ESV 2-part. I have set up an auto water changing system and have programmed my apex to change out 1 gallon, 2 times per day (8:30AM & 8:30PM) on a system with 20 gallons of total water volume. Are 2 5% water changes per day enough to maintain stable and appropriate calcium, alkalinity, magnesium, and trace elements as well as removal of fish waste and control nitrate and phosphate levels? I am currently using Red Sea Coral Pro as my salt mix for NSW and my NSW and RODI containers are each 20 gallons therefore I can go 9-10 days of water changes between NSW mixing sessions.

 

[sghera64]

How much of each 2 parts do you have to dose each day?

 

[bgoldb]

About 11 ml.

 

[Randy Holmes-Farley Verified Community Expert]

That's about 1.2 dKH per day.

I've done such calculations here already. It takes a massive amount changed (20-50% daily) to keep up alkalinity unless the demand is super low. You will need to change more than 15% daily. Probably 20-30%.

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

 

[Randy Holmes-Farley Verified Community Expert]

FYI, at 1.2 dKH per day demand, you are in between Figure 23 (0.56 dKH per day) and Figure 24 (2.8 dKH per day)