Chemistry question

[Joker79]

For the last week I have tested my tank to prepare for my dosing pump. <br />
started as follows:<br />
Day 1 <br />
Alk 9.6<br />
Cal 450 <br />
Mag 1290 <br />
Dosed mag to increase to 1350 over the next few days<br />
<br />
The last 3 days my readings have been:<br />
Alk 9.9<br />
Cal 450 <br />
Mag 1350<br />
<br />
Salinity 1.025 to 1.026<br />
Temp 81 <br />
<br />
<br />
What would cause no changes in my Chem levels of over a 3 day period?
Any help would be greatly appreciated!

 

[Randy Holmes-Farley Verified Community Expert]

Can you tell us about the tank?

Those values might not change over 3 days in many tanks.

 

[Joker79]

Absolutely. What would.you like to know?
Stock is
Estimated 100 plus zoas
4 mushrooms
3 sps
5 chalice colonies
2 acan colonies

 

[Randy Holmes-Farley Verified Community Expert]

How big are the hard corals and are they growing well?

Is coralline growing well?

The zoas and mushrooms will have almost no impact on calcium, alkalinity, or magnesium.

 

[Joker79]

1 acan colony is roughly 30 heads
The sps are continuing to encrust with growth tips.
I ish my phone would let me load some pics. File size is too large it says.

 

[Randy Holmes-Farley Verified Community Expert]

It could just be that the demand is not that noticeable over a 3 day period.

I'd watch it for a week and see how much alkalinity changes. We can calculate how much calcium and magnesium will change if we know the alkalinity change, so there's not that much need to measure them very often, and they change far more slowly.

 

[Joker79]

How would I measure the Cal and mag based upon alk reading?

 

[Randy Holmes-Farley Verified Community Expert]

Not the reading, but the decline.

Calcium cannot drop more than about 6 - 7 ppm per dKH of alkalinity decline, and magnesium would decline less than 1 ppm per dKH of alkalinity decline. So alkalinity will change a lot faster and is the indicator to look to to determine if you need to dose anything.