Raising MG

[Furnman]

Testing results showed my mg at 800. I have about 130 gallons of water. Using the Reef Chemistry Calculator I learned that I needed to add about 94 oz. of epsom salt to raise my mg level to 1350. It says not to add more than 100 ppm / day.

How do I calculate the weight of epsom salt to add / day?

 

[psteeleb]

if you are going to raise it from 800 to 1350 or 550 ppm just do it over a week (consider checking your results first - that's low)

or divide the 94oz by 5.5 (17oz per day)

HTH

 

[jdieck]

First of all, check the testing. If you have been doing some regular water changes it is very unlikely you have 800 ppm. Take a sample to the LFS or to a friend aquarist and test it again. There is nothing worst than fixing something that is not broken.

Second, if it indeed is that low, using Epsom Salts in that quantity will really create a n ionic unbalance increasing the sulfate portion significantly.
For such a large adjustment I would use the DIY mix of 10 parts magnesium chloride and 1 part epsom salts. Alternatively use a comercial additive. My favorite is Kent's Tech-M for it's concentration.

 

[psteeleb]

+1

 

[Bri Guy]

What salt mix do you use? At what salinity?

Mix some fresh SW up and test the Mg. Double check your findings before making a major adjustment like that.

Good Luck!

 

[jdieck]

Yes, forgot to mention that a low salinity may lead to low level measurement of ions. So as mentioned by Bri above, double check your salinity level.

 

[Furnman]

I've been using Instant Ocean & my salinity is 1.025.

I've been measuring mg w/ a brand new elos kit and have been getting the 800 ppm consistently.

Could my low mg reading have to do well water?

 

[FourWindsDealer]

In a 130g system, 17.1 oz Epsom salts are required to raise Mag by 100 ppm.

Reef Calculator

 

[Billybeau1]

Instant Ocean has mag in the vicinity of 1100 ppm at 1.0264 so at 1.025, it will be slightly lower.

I'm with jd in that your mag may be a little higher than 800 ppm.

Either way, One option is to switch to a salt mix with higher magnesium levels. My salt mix thread at the top of this forum will guide you for higher magnesium salt mixes that my be available to you.

If you are using well water, I hope you are running it through an ro/di filter first.