How fast can Alkalinity drop?

Daniel Troconis · Nov 8, 2018

Hi FAM: I tested on
Sunday Before Water Change: 97ppm = 5.42dkh
Sunday After Water Change 122ppm = 6.82dkh
Thursday four days later I now have 104ppm = 5.81dkh

1-Does anyone know how fast and or what should I expect as far as decreased ALK parameters after just four days?

2-Should I start dosing?

20 Gallon tank (nuvo fusion)

1 Six line wrasse
1 Anemonie
Corals: yes plenty see photo around 20 different species + wall of GSP
1 Shrimp
1 Emerald crab
1 turbo snail
8 small snails
3 hermit crabs
1 Clam small

Chaeto reactor (hang on back)

Dr. Reef · Nov 8, 2018

depending on the tank i have seen 1-4 dkh drop per day.

Dr. Reef · Nov 8, 2018

you need to log daily for a little while seeing what alkalinity levels are. after you have a week or 2 worth of daily alk levels you will see a pattern of how much alk your tank consumes per day. Once you have that value then you start dosing accordingly.

DenverSaltyFarm · Nov 10, 2018

Wow great looking tank. That is a very slow drop. My tank will drop 1-2 dKh per day if I took my calcium reactor off line. Personally if you are jumping 1.41 instantly after water change that’s a big jump you really should keep your alk as steady as possible

Fishfinder · Nov 10, 2018

Also 5-6 dKh is well below the norm. Not saying it isn't possible. But I would try a new test kit maybe

JMetaxas · Nov 10, 2018

I dose daily. Its part off owning a reef tank. You should too.

catfishblues · Nov 10, 2018

It will vary depending on how much your corals are removing calcium and all that out of the water. In my tank it takes a week or two to go down 1 dkh. I have about as much or more coral as you but mostly softies and some small lps. Test with a good test kit frequently for a little to get an idea and you'll know if you need to start dosing or not. When keeping Stony corals, clams, Coraline algae, and to a degree softies at some point you'll need to probably start dosing but newer tanks and those that don't take up much can get by on water changes.

Randy Holmes-Farley · Nov 10, 2018

The daily alk drop at 5 dKH will be very low. The daily alk drop at 8 dKH will be far higher in the same tank.

Daniel Troconis · Nov 10, 2018

I did a small 2 gallon water change last night and it went up to 114ppt = 6.37dkh, I believe that this LOW ALK is what is keeping my tank in a slow growth and all zoas are like shrinking instead of growing, in facct all corals take too long to grow anything.