Water Parameters

[AngryOwl]

Hi everyone, wondering how to manager my parameters to get them to the right level... really only calcium is not where I want it to be. Is it not advised to dose 2 part calcium to get it where I desire (420)? Tank is lightly stocked with corals, details on tank below.

Tank:
120g
120lbs live rock
1 inch sand bed
Trigger systems emerald 39 sump with water level at 9.5 inches.

Parameters:
Alk: 7.9 - Hanna
Cal: 375 - Red sea
Mg: 1360 - Red Sea
NO3: 4ppm Red sea tested both low & high
PO4: 0 ( I'd like to raise this, I have bought Neophos, dosing recommendations/tips welcome)
Salinity: 1.025

I tried dosing some magnesium like 1 1/2 or 2 weeks ago and used BRS calculator to do so... and it way over shot at it was at 1500... I haven't done anything to the tank besides add more coral since then and now it is down to 1360 which seems like a steep jump to me. My Alk has been stable since I got my Hanna checker.

11/28: 7.9
12/02: 7.8
12/03: 7.9
12/04: 7.9

Everything is pretty much where I want it to be accept calcium. I don't really water change this system so please don't advise me to water change until the levels are corrected.

According to BRS calculator if my total system volume is 120g I would need to dose 550mL to bring calcium from 375 to 420.

 

[McMullen]

Yes dose.
550ml?!

 

[AngryOwl]

Yes dose.
550ml?!

Right?! I was just gonna bring it up real slow over a couple days, no rush... but you're saying it's fine just to dose only calcium until desired level reached? And then from there does equal parts based off alk?

 

[McMullen]

Always dose only whats needed. Slowly

Despite what is commonly reported my tank has never required equal parts calcium and Alk.

 

[Heliarc19]

Right?! I was just gonna bring it up real slow over a couple days, no rush... but you're saying it's fine just to dose only calcium until desired level reached? And then from there does equal parts based off alk?

When you say your tank is 120gallons is that the tank size or water volume? I always start at 1/4 or 1/2 what the calculators say then test to see the change

 

[AngryOwl]

When you say your tank is 120gallons is that the tank size or water volume? I always start at 1/4 or 1/2 what the calculators say then test to see the change

Yea I'm estimating 120g with sump and minus rock and such.