Learning to dose manually - Questions!

[PTXReef]

Hello!

I am learning to dose baked baking soda once I got my hanna checkers to raise my tank's alkalinity from 6.5 dKH to 8-9 dKH.

My current parameters are:
Salinity: 1.026 sg, 34.0 ppt
Temperature: 78.8 F

API Saltwater Test Kit:
pH: 8.2
Nitrites: 0 ppm
Ammonia: 0 ppm (I do not think this is accurate)
Nitrate: 5 ppm

Hanna Checker:
Alkalinity: 7.8 dKH
Calcium: 575 ppm

Red Sea Foundation Pro Multi Test Kit:
Magnesium: 1740 ppm?

My question is, why is the magnesium too high (is it possibly an inaccurate result)? Does this seem balanced? I also recently switched over from Instant Ocean Sea Salt to Red Sea Coral Pro (very slow 5 gallon water changes in a 95 gallon system weekly making sure not to raise alkalinity more than 0.5 dKH a day).

So far all corals, inverts, and fish look happy but would like to avert any potential disasters if the parameters are getting out of whack...

Thanks in advance! Happy Reefing !

 

[Sierra_Bravo]

First, calibrate your refractometer and/or have your water tested by another means and make sure your salinity is accurate. Your calcium levels are a little high as well and this can happen if your salinity is higher than what you believe it to be. I had my calibration fluid evaporate in the bottle over a period of time and this caused my refractometer to report incorrect low readings. My calcium and mag trended higher as this progressed.

Next, check how you are conducting the Red Sea magnesium test. A lot of people get bad readings if the directions are not followed exactly. You add one drop of reagent A at a time, mixing for 15 seconds between each drop for a total of five times. It seems this gets missed quite a bit.

 

[PTXReef]

First, calibrate your refractometer and/or have your water tested by another means and make sure your salinity is accurate. Your calcium levels are a little high as well and this can happen if your salinity is higher than what you believe it to be. I had my calibration fluid evaporate in the bottle over a period of time and this caused my refractometer to report incorrect low readings. My calcium and mag trended higher as this progressed.

Next, check how you are conducting the Red Sea magnesium test. A lot of people get bad readings if the directions are not followed exactly. You add one drop of reagent A at a time, mixing for 15 seconds between each drop for a total of five times. It seems this gets missed quite a bit.

Good suggestions! I am using the IceCap Salinity/Temperature Digital Pocket Tester (SPt03 model). I have been using this for 6 months now (had to get an older model replaced because its readings were off when I checked against my LFS's tester). Will test side by side with tester from LFS.

As for the Red Sea magnesium test, I will retest. All instructions have been followed exactly as stated.

 

[PTXReef]

7/29/2020 Update:

Retested water parameters and still at high magnesium, stopped dosing baked baking soda.

My current parameters are:
Salinity: 1.025 sg, 33.6 ppt (will lower to 33.0 ppt)
Temperature: 78.8 F

Hanna Checker:
Alkalinity: 7.5 dKH (-0.3 dKH difference from day before)
Calcium: 530 ppm (-45 ppm difference from day before)

Red Sea Foundation Pro Multi Test Kit:
Magnesium: 1740 ppm (still the same!)

 

[PTXReef]

7/30/2020 Update:

Retested water parameters and still at high magnesium but calcium dropped 90 ppm, stopped dosing baked baking soda.

My current parameters are:
Salinity: 1.026 sg, 33.8 ppt
Temperature: 78.6 F

Hanna Checker:
Alkalinity: 7.5 dKH (Did a 5 gallon WC with 12 dKH fresh SW, raised from 7.2 dKH to 7.5 dKH)
Calcium: 437 ppm, 442 ppm (-90 ppm difference from day before)
Tested twice to make sure. Why did it drop so dramatically? Due to the 5 gallon WC?

Red Sea Foundation Pro Multi Test Kit:
Magnesium: 1700 ppm (Dropped ~40 ppm)
Tested Twice and followed manufacturer instructions exactly.