Alk Dosing Question

[sledge75]

I was just wondering if what I'm experiencing was normal or if there is something to be concerned about. I dose B-Ionic for my Ca and Alk; however, lately the Alk has needed more dosing than the Ca.

Parameters:
NH4 0
Nitrite 0
Nitrate 0
Ca 425
Alk 8.8 dKh (~3.2meq/l)
pH 8.18-8.30
Salinity 1.026
Temp 80.5-80.7

For a while when the tank was newer and I only had coralline growing I was dosing a bit of B-Ionic each morning and keeping things very steady. Now that I have some corals I've upped the dosing which keeps Ca steady at 425 but the Alk kept slowly dropping over the week down to 7.9dKh. Dosing much more Part 1 caused pH to rise as well.

So what I've been doing now is dosing about 8ml of parts 1 and 2 in the morning and 1/2 tsp of baking soda in the evening. Everything is nice and stable over the week and the corals are showing noticeable growth, but I was just wondering if it was normal for the Alk to be used up faster and if so why.

Sorry for being longwinded but I would appreciate any insight.

 

[Liam]

As your tank matures and possibly your bio-load increases so do the accumulated acids in your system in your sand bed etc,this could be why you are having to dose more Alk to overcome these acids,they will also have the effect of lowering your ph.This is all common as sytems age.

 

[sledge75]

That seems to make sense. So over time would you expect this to level out and things to stabilize such that Ca and Alk usage are more equivalent?

 

[Liam]

That seems to make sense. So over time would you expect this to level out and things to stabilize such that Ca and Alk usage are more equivalent?

They won't neccessarily be equivalent,but they should stabilize to the extent that you can dose more consistantly to replace them.Calcium uptake will be directly related to the amount of calcifying organisms you keep i.e if you add more sps your going to need to dose more calcium.Alkalinity requirements will also increase as above but can be more inconsistant due to varying feeding levels rates of denitrification etc.
I think that sounds about right clear as mud,right?

 

[NateHanson]

I would also work your alk up to about 4 or 4.5 meq/L. 3.2 is a bit on the low end IMO.