Using aquaforest magnesium chrystals/powder.

[mucky1957]

Help please.
I bought the aquaforest chrystals as I wanted to make up a stock liquid for maintianing the mag levels.
I keep adding about 50ml twice a day (for a while now) and my salifert test kit shows the level is still under 1300.
I have to assume that the amount of chrystals I added to my 2lt tub of RODI is wrong. I was told to use 20gm ??
Can anyone who using aquaforest tell me how much I should add to 2lt of RODI to have the correct magnesium strength.
Is there some way to test the 2lt tub to check that it is the right strength or not ? I assume there isn't.
Thanks.

 

[Randy Holmes-Farley Verified Community Expert]

The amount one uses for any supplement depends on the tank water volume, which you did not mention.

I'd also be wary of accepting magnesium test results. They are inaccurate enough that I do not recommend testing it. try the kit on some new salt water.

Low magnesium is often due to low salinity, and raising salinity is the way to raise magnesium, if low salinity is the cause.

https://www.reef2reef.com/threads/just-say-no-to-magnesium-testing-rmm-is-born.1017528/

 

[mucky1957]

apologies..the tank has 200lt of water.
I get my salt water from a vert trusted source so I do not believe this is an issue.

 

[Randy Holmes-Farley Verified Community Expert]

apologies..the tank has 200lt of water.
I get my salt water from a vert trusted source so I do not believe this is an issue.

The point of the suggested test is to see if the kit is reading low, not primarily to assess the quality of the new water. But since you don't know (?) what the water is made from, then perhaps it isn't that useful anyway.

Do you know the tank salinity?

Again, I warn against just blindly adding magnesium from a single test result as you may make a minor problem worse, but if you want to boost magnesium by 50 ppm in 200 liters using that solid magnesium supplement, you would need to add ALL of 85 dry grams of that supplement.

If you dissolve 20 g of that solid in a liter (as you did), you would need to add 4.25 liters.