Need help from the big dogs w/calcium&kh

Yeah it will drop.
I am kinda leaning toward a combo approach here.
Water change and after a couple days, recheck, then possibly add some buffer.

How are you adding the supplement? Do you have an auto top-off method going on for evap or is this by hand?

 

You should check your Magnesium levels. Mag will keep Alk and Ca on check....

 

Glad to hear it. I'd give it a day or so, test and repeat.. then maybe start to raise the alk.

I thought about adding supplements to my evap water before, but I ruled it out. I think it's too risky and, as you are showing, hard to calibrate to the needs of your tank that way. On a real hot day, you will add more. Less at other times. I would separate the supplement dosing for these reasons so you are adding what your aquarium requires.

Great point. That often gets overlooked compared to alk and calcium. My experience showed that when I kept the magnesium up (I shot for 1300-1400) the others balanced out a bit. Magnesium went pretty quickly in my last tank too. Worth testing with the others.

 

Hey thought I'd chime in.

I would with out a doubt use a buffer to increase your ALK. Getting your ALK up will help form stopping a possible snow storm. you'll never get it in balance with a CA of 650 so water changes will have to help with that.
Increasing your SG will raise both your ALK and CA but I would recommend you get it up to 1.026.


I would also check you CA test kit (sorry if that has already been asked) but at 650 I would suspect your sand bed would be solid.

 

I'd really look into a new Test kit. or take some water into a LFS to have it tested. I would hate for a faulty test kit to have you running around lowering your CA when it's currently OK. IMO an SG of 1.026 is the recommended SG for a reef tank. Some run lower but 1.024 is about as low as I would go.

How are your Corals and inverts doing?

 

get a mag test.. and if the mag is around 1200 then buy a new ca test..

if you write 650 mg/liter it's nearly impossible as you should have milk water...

let calcium be "eated" by corals.. not to deposit on the tank or you will have a calcium rain in water and it will never come back to water (cant dissolve in tank water..)

so if it's really so high let the corals eat it.. but check Mg.. if you have not a good Mg the calcium wont be used..

kh depends also from pH, temperature, and CO2 in the water.. you may have too much co2 dissolved

i'll wait ..