Ca and Mag supplementation for fresh mixed water

[maroun.c]

Hi,
Just opened a new RC bucket and I'm getting the following for 24 hours fresh mixed water:

Sal: 1.025
Ph: 8.37
Temp: 80
Alk 12.2
Ca 370
Mg 1095

Current tank parameters:
Sal 1.025
PH 8.2-8.4
alk 8.3
Ca 380 (bringing it up to 420 +)
Mg 1140 (bringing it up to 1300)

Do you think I should supplemnt the fresh mixed water to avoid bringing my parameters down and messing up my 2 part daily dosage? Should I supplement in the salt mixing bucket or in the tank after the water change reason for this question:
- will added Ca precipitate if added in mixing bucket where alk is 12 .2?
-If I perform the water change and then supplement wouldn't that cause to much fluctuations for the fish to handle?

Last question, is about alk would a 30G water change with water at 12.2 shock a 150G tank where alk is at 8? I used to use 50% of Crustal sea marine mix with an alk of 9 to lower it down but it has very low ca (300) and Mg (960) and ended up to costly to supplement.
Thanks for your help.

 

[Randy Holmes-Farley]

I'm surprised the calcium and magnesium would be that low. How much of a container of salt mix did you make up?

 

[maroun.c]

Its a bit less than 30 G.
Will retest with a different testkit tomorrow as I tested it with Salifert which I as I've read isn't the best testkit for Ca?
Any info if supplementing pre water change will cause some precipitation?

 

[Randy Holmes-Farley]

No, boosting calcium and magnesium to normal levels will not cause precipitation at 12 dKH, as long as you do not drive up the pH somehow.

 

[maroun.c]

Thanks.

 

[Randy Holmes-Farley]

You're welcome.

Good luck.