KH usage on NEW tank with NO corals... where is it going?

[Dukereefnz]

Hi – I have a few questions regarding my new reef tank.

I have cycled my tank with live rock in the sump and dry rock in the tank
Used Bac7 and a shrimp to start cycle
Continued to add 5mls Bac7 daily

After the cycle the KH dropped to 6.44 dKh I have added baking soda slowly to bring it up to 7.36dKh
I need to add a small amount of baking soda each day to maintain the KH level….

I read that the KH level will drop during a cycle, but I expected it to level out once lifted back up to 7.5, but it will slowly drop.

Questions

• Is it Ok to add baking soda dissolved in RO water each day to maintain KH?
• Why is my KH level dropping when I have No corals

200G plus sump – no coral at this point & lights are off..
Salt 35ppm
KH 7.36
PH 8.46
Temp 24.8
Phosphate PO4 0.06
Nitrate NO3 3.3

The tank has been running about 4 weeks, test kits are Hana or Reef Factory

Fish
1 x Brown Tang
2 x clown

 

[trevorhiller]

Either his comments, or your interpretation of them, are seemingly not correct. We do know what depletes alkalinity, and the only thing that is significant in a reef tank (aside from calcification) is conversion of ammonia to nitrate. That depletes alk. A rise in nitrate by 50 ppm will deplete 4.5 dKH or alk.

There is not a big list of other "processes" that deplete alkalinity. No other normal processes by algae or bacteria or anything else deplete alkalinty.

Bear ion mind that many organisms form calcium carbonate and deplete alkalinity. Worms (some types), snails, bivalves, etc. can deplete alkalinity. Abiotic precipitation of calcium carbonate is also often significant and can be the major sink in a new tank.

-Randy Holmes-Farley here:

Alkalinity decline without coral

My 110 gal tank is a few months old, and pH was around 7.6 and alkalinity around 5-6 (Tropic Marin Pro). I'm trying to raise my alkalinity and pH by dosing baking soda (in RODI). I've gotten alkalinity up to about 8.5 (pH is about 8). Alk goes up by about 0.5 dKh after I dose, but then over a...

www.reef2reef.com

 

[Dukereefnz]

Thanks for the reply... I had a closer look with a torch

calcification.. I am seeing Coralline growing in my sump and little purple spots on my dry rock, so that will explain the drop. As far as ammonia that was reading zero... I had the life rock cycling in my shed for a couple of months.. only dry rock in DT.

 

[Dukereefnz]

Coralline is growing.. very cool. I have to get my CA reactor working at some point. But for now is baking soda OK?
About to read the post link - thanks

 

[Dukereefnz]

Great link .. thanks so everything is as expected.
Once KH usage slows down I will be ready for lights on and coral... I am trying to beat ugly stage...
thanks All.