Balancing calcium, alk, and magnesium

quicksil328 · Mar 8, 2016

Hi everyone, I am sure questions like this have been asked many times but I am new so I am going to ask anyway. I have a mainly fowlr tank right now but I am starting to dabble in coral keeping. I have two frags right now. I have a small hammer frag and a zoa frag. My main display is 190 gallons with a total water volume of around 250 gallons with my sump. I do water changes every 10-14 days of approximately 50 gallons. I also run a two little fishes 150 gfo reactor and I am pumping water up to a second sump/refugium of sorts to a large basket of chaeto (gravity feeding back to main sump). Currently my water parameters are :
Sg - 1.025
Ammonia-0
Nitrite-0
Nitrate-0-5
Ph- approx 8.1
Dkh-12
Calcium- 360-380
Magnesium-1600

SO my question: I believe my magnesium and dkh are too high in relation to that of my calcium. I have read that many keep their calcium between 400 and 450. I have read conflicting reports on calcium and I am confused to say the least. I have Seachem reef fusion 2 part dosing (calcium and alk) but I am not sure if I should dose at all, dose both, or if I can just dose the calcium. Any help would be greatly appreciated.

Randy Holmes-Farley · Mar 8, 2016

FWIW, it is not desirable, IMO, to target levels is relation to one another. All of them independently have desirable level and undesirable levels, and just because one might be high or low is not a reason for the others to be that way.

Since you want to boost calcium, you need to use a calcium only supplement, which is typically calcium chloride. There are many brands and you can buy unbranded calcium chloride from places like BRS or Dr Foster and Smith if you prefer.

This calculator shows how much to use:

http://reef.diesyst.com/chemcalc/chem_calc3.html

and this has my suggested levels and the reasons for them:

https://www.reef2reef.com/threads/o...-reef-aquarium-by-randy-holmes-farley.173563/

quicksil328 · Mar 8, 2016

Thanks. I wasn't sure if I should be doing something (such as dosing) or not. There is so much information available it is a little overwhelming honestly. It just seemed like my magnesium was high and I wasn't sure how concerned I should be about it.