Kalk question

[Dozer1one]

I have decided to start dosing kalk via drip line, due to my calcium usage in my mixed reef tank, currently my tank consumes roughly 40 ppm daily of calcium, as it stands today my calcium is down to 360ppm and my alk is 10.5 dkh.
If I start dosing kalkwasser what will it do to my alk?
It seems that alk measurement is rather high vs my calcium.... Why?
Also is 40 ppm daily consumption of calcium normal, it turns out to be 280 ppm usage in between water changes. I test regular using salifert test kits and double checking with a friends test kits also salifert

 

[Randy Holmes-Farley]

I have decided to start dosing kalk via drip line, due to my calcium usage in my mixed reef tank, currently my tank consumes roughly 40 ppm daily of calcium, t

Not likely to be accurate. How did you determine that?

You need to measure over a long time (like 2 weeks) to accurately determine the calcium usage because test results jump around too much due to inaccuracy.

If you determine your alkalinity demand (which is easier), you can calculate the calcium demand.

At 40 ppm per day calcium demand, you'd need to be loosing close to 6 dKH alkalinity per day.

You should also determine the dose of limewater to match the alkalinity demand for this reason, not by calcium.

Have you accounted for the calcium changes by the water change itself?

 

[Dozer1one]

Hey randy, I have tested over the last 9 days, I do my water changes on tues which is when I got my reading of 440ppm, wed 400 ppm, thurs, today 360 ppm.
Same trend as last week. This was tested using a up to date salifert and just double checked with my friends salifert as well, which is why I decided to ask here. A little more info on my tank is it's a 92 heavily coral populated mixed reef, but only 6 medium to small sps, the calcium intake naturally went up when I put those in there. Why would the cal be so low and the alk so high?..... Assuming test results are accurate

 

[Dozer1one]

Also I use Red Sea coral pro and keep my salinity at 1.025

 

[Randy Holmes-Farley]

Are you adding any alkalinity?

You should have lost 11 dKH to match that calcium drop, and there is no other way for calcium to drop that does not take up that alkalinity, aside from a water change.

 

[Dozer1one]

I have been doing weekly water changes 32 gal on a 92

 

[Dozer1one]

No added alk, I have one reactor with phosgaurd in it due to some Gha that's almost gone now, the reactor is about to be taken off line

 

[Dozer1one]

I just checked it with an API test kit and the calcium reads 400 ???? Could the junk API actually be right? I double tested.

 

[Randy Holmes-Farley]

I suspect a calcium testing error of some sort if the alk has not declined.

 

[Dozer1one]

Ok.... So I purchased Red Sea test kits last night and double checked all parameters.. Seems my salifert were way off???? I don't know why as they are all newer test kits but, Red Sea
Shows my calcium at 400 my alk still at 10.5 and my mag at 1100, as I stated before I did my water change 3 days ago so I will resume testing over the next week or two and see what my daily usage is.... At what point do I say to myself, start dosing

 

[Randy Holmes-Farley]

You might dose some magnesium, but calcium and alk are OK now, and I'd suggest dosing to keep them where they are. So dose a bit when they drop.

 

[Dozer1one]

Ok will do. Thanks for your help

 

[Randy Holmes-Farley]

You're welcome.

Happy Reefing.