need help with math and magnesium dosage

[711reefer]

i am not the sharpest with math and need some help. my mg levels were 1200 and my target is 1300. i use seachem mg reef advantage ( dry stuff ) i added 50 grams and achieved a reading of 1280. how many more grams do i need to raise it another 20 so i am at target of 1300. thanks..

 

[Gareth elliott]

What is your water volume?
Calculator for the product you have.
http://www.seachem.com/reef-adv-magnesium.php

 

[Heliarc19]

12.5 grams

 

[NY_Caveman]

In the most simplistic math terms, if 50 grams gave you 80% of your dose you would need 12.5 grams more.

 

[Crashjack]

i am not the sharpest with math and need some help. my mg levels were 1200 and my target is 1300. i use seachem mg reef advantage ( dry stuff ) i added 50 grams and achieved a reading of 1280. how many more grams do i need to raise it another 20 so i am at target of 1300. thanks..

If 50 grams raised Mg by 80 then 50/80*20=12.5 grams.

 

[711reefer]

i didnt even think of 80 percent. now it makes sense. thanks

 

[Jr'sReef]

50g = 80
25g = 40
12.5g = 20
6.25g = 10

I like to break things down by halves lol

 

[711reefer]

i am not sure how much i trust the calculator. i am using a fresh red sea mg test kit. i believe i have 55 to 60 gallons of water volume. 50 grams moved my reading 80 points. according to that calculator i have about 13 gallons of water.

 

[Gareth elliott]

I find Magnesium test kits are not always the most accurate, (or any hobby grade tests, for an exact number anyway). i personally use mg tests to get in the ball park Within the range of my salt mix. For your reading Say theres even a 1% error thats a range of 1267-1293.

 

[711reefer]

i agree most test kits arent extremely accurate. the seachem website was saying i should use about 261 grams based on 55 gallons of water. i am only needing about 62.5 grams.

 

[Randy Holmes-Farley Verified Community Expert]

i am not sure how much i trust the calculator. i am using a fresh red sea mg test kit. i believe i have 55 to 60 gallons of water volume. 50 grams moved my reading 80 points. according to that calculator i have about 13 gallons of water.

I'd trust a calculator before a test kit, especially that one.

FWIW, the calculation is correct if your water volume assumption and the starting and final values are correct.