Two Part Dosing Question...CA rose by itself?

techytechguy · Apr 5, 2022

Hi all,

So far I have been fine just doing water changes because I had very few corals and even those are LPS and softies. I have started to add more corals now. Recently I noticed that my Acans were looking sad. I tested my params and Alk was at 5.8 and CA was at 200

.

Anyways, I decided to start dosing now but I had to bring the levels back to normal first. I am using BRS two part (Soda Ash and Calcium Chloride). I know you are supposed to dose equal amounts but I decided to raise ALK by 0.3 per day and CA by 20 ppm per day. BRS calculator was showing 24 ml of Alk and 235 ml of CA dosing per day if I went by this which is almost 10x difference not equal amounts as I expected. Anyways, after doing it for a few days ALK is up to 7.4 but I was surprised that after 3 dosings CA is already up to 470. I was surprised because I was expecting CA to be around 300.

I am using Hanna checkers or both Alk and CA. I did repeat the measurements to make sure it wasn't a measurement mistake.

So, just wanted to understand if CA rising so much is expected and should I have been equal amounts all along?

Spare time · Apr 6, 2022

Do you use distilled water for the hanna calcium test?

ffmurray · Apr 6, 2022

My understanding is if you have mostly soft corals you won’t be using as much calcium… so dial that back. I found as I added SPS my calcium demands went up. Have you looked into kalkwasser? What about baked banking soda? Look up Reef chemistry calculator in the search if you’re not already

Randy Holmes-Farley · Apr 6, 2022

Calcium at 200 ppm was very likely test error to begin with.

Randy Holmes-Farley · Apr 6, 2022

ffmurray said:
My understanding is if you have mostly soft corals you won’t be using as much calcium… so dial that back. I found as I added SPS my calcium demands went up. Have you looked into kalkwasser? What about baked banking soda? Look up Reef chemistry calculator in the search if you’re not already

Soft corals certainly use less calcium AND alkalinity, but they do not use alkalinity and less calcium. They use the same ratio of 2.8 dKH (1 meq/L) for each 18-20 ppm calcium as all organisms in the aquarium that use any alkalinity.