Calcium dip of 50ppm???

[Jake_the_reefer]

So I am a little confused. I started to track my calcium using both a salifert and hanna checker to get a good reading every night. They are usually 5ppm within one another so I am confident my readings are accurate.
Nov 20 450ppm
Nov 21 441
Then today
395ppm (salifert was 405 for some reason)

But my question is, how can I have such a big dip in calcium all of a sudden? I have been dosing alkalinity lately and letting my calcium drop so I can figure out my daily dose for it. I notice no precipitation as well of calcium.
Is it possible that now that I have kept all stable at 8.0 the last 2 weeks calcium usage has sky rocketed while before alk was around 6.5? I use about .3 dkh per day of alk.
Tank is heavy lps and some sps.
Should I dose calcium tonight or keep letting it drop so I can actually figure out my daily usage.

 

[Bigwrasse]

I would go ahead and dose it. Get it back to where you want it and test daily at the same time for a few days to figure out the daily dose

 

[Jake_the_reefer]

I would go ahead and dose it. Get it back to where you want it and test daily at the same time for a few days to figure out the daily dose

How much can I raise it safely? I've only dosed alk thus far never had to do calcium. I just now dosed alk so I guess in 40 mins I can do calcium

 

[madweazl]

Simple answer is it didnt. Do not dose this, it isnt accurate. If you have an ATO, you may want to double check your salinity but your calcium didnt drop 50ppm, period. Also, there is no reason to test your calcium daily, give it a good week and figure our your daily consumption that way. Based on your alkalinity demand, your calcium would have only dropped 2ppm.

 

[Bigwrasse]

I would raise it about 25 ppm today and 25 ppm tomorrow

 

[Jake_the_reefer]

Simple answer is it didnt. Do not dose this, it isnt accurate. If you have an ATO, you may want to double check your salinity but your calcium didnt drop 50ppm, period. Also, there is no reason to test your calcium daily, give it a good week and figure our your daily consumption that way. Based on your alkalinity demand, your calcium would have only dropped 2ppm.

My salinity does seem low for some reason. The other day it was 1.0255 now its 1.023 what's weird is my top off did seem to over fill but it's only like a quarter inch higher than normal so that shouldnt have made a huge swing. I can do a 20% water change but that will probably throw off the fact I just dosed alk

 

[Jake_the_reefer]

Actually I'll do a water change tomorrow after work. I need to mix up some rodi but too late tonight

 

[Randy Holmes-Farley Verified Community Expert]

For calcium to drop 50 ppm over time, and if the salinity is unchanged, alk will have needed to drop by about 7.5 dKH. If you might have added that much then calcium may have dropped that much.