When to tweak alkalinity maintenance

[Duane Clark]

I have a small 14g mixed reef. I use kalk plus calcium and mag in my ato to maintain these elements. My kalk is maxed out at 2 tsp per gallon of RO/DI. I am seeing my alk decrease by .25 to.3 dkh daily. Calcium and magnesium also decrease a bit but seem to be maintaining at “normal” levels. As a result of this alk Decrease I am seeing weekly fluctuations by a little over 1.5 to 2 dkh by the time I refill my ATO. I then have to add sodium bicarbonate each week to return it to my desired 9.1 to 9.3. Is this fluctuation acceptable or do I need to tweak something here to maintain a constant 9.1?

 

[Palyzoa]

That doesn't seem to be that big of a swing. You always want to dose the different elements separately to avoid precipitation. Of course you could get a doser down the road if you don't want to manually dose.

 

[Duane Clark]

That doesn't seem to be that big of a swing. You always want to dose the different elements separately to avoid precipitation. Of course you could get a doser down the road if you don't want to manually dose.

Stupid question but would it make sense to dose just a sodium bicarb solution via a doser or get rid of the kalk in the ATO all together and do two part for such a small tank?

 

[chipmunkofdoom2]

The reason you are seeing the fluctuations is because you are not dosing equally. Calcium hydroxide (kalkwasser) supplies calcium and carbonate alkalinity. This is a balanced additive, and if you dosed calcium hydroxide alone, calcium and alkalinity would fall at the same rate. The reason alkalinity is falling faster than calcium is because you're dosing additional calcium and magnesium in the ATO. Basically, you are dosing 1x alkalinity, 1x magnesium, and 2x calcium (this may not be proportionally correct based on the quantities you're using, but it's a rough approximation of what's going on).

If you are dosing calcium chloride in your ATO, you should be dosing a sodium carbonate or sodium bicarbonate solution in equal proportions. I would personally not dose calcium and magnesium in the ATO. I would prefer the control of having them on their own additional dosing pumps.

 

[Duane Clark]

The reason you are seeing the fluctuations is because you are not dosing equally. Calcium hydroxide (kalkwasser) supplies calcium and carbonate alkalinity. This is a balanced additive, and if you dosed calcium hydroxide alone, calcium and alkalinity would fall at the same rate. The reason alkalinity is falling faster than calcium is because you're dosing additional calcium and magnesium in the ATO. Basically, you are dosing 1x alkalinity, 1x magnesium, and 2x calcium (this may not be proportionally correct based on the quantities you're using, but it's a rough approximation of what's going on).

If you are dosing calcium chloride in your ATO, you should be dosing a sodium carbonate or sodium bicarbonate solution in equal proportions. I would personally not dose calcium and magnesium in the ATO. I would prefer the control of having them on their own additional dosing pumps.

Makes sense. to try and avoid dosing out of balance I use this product (see pic). My hope was that the components were balanced already. Just to clarify though...the calcium and mag are also slowly decreasing as well but they were VERY high to start out with (I assume the corals are catching up with the calcium and mag). The Frite Pro salt I use has high Ca and Mag from what I understand.

 

[Randy Holmes-Farley]

Makes sense. to try and avoid dosing out of balance I use this product (see pic). My hope was that the components were balanced already. Just to clarify though...the calcium and mag are also slowly decreasing as well but they were VERY high to start out with (I assume the corals are catching up with the calcium and mag). The Frite Pro salt I use has high Ca and Mag from what I understand.

The alk and calcium are close to balanced (slightly more calcium than alk long term).

But don't accept the manufacturer assertion about magnesium in it. It's a no go on magnesium (too little by far, and what is there won't dissolve), despite the claims.