Question about brs two part.

[lost in it all]

I have been using BRS two Part for six months now and with the new 300 gallon system I can not seem to keep mag high enough. I have gotten everything to the desired level then start doing daily doses and by time the gallon of calcium is gone my mag has dropped at least 200 ppm and BRS's calculator says I need around 200 fl oz to get it back up around the 1350 mark I am not sure what I am missing that it would keep doing this?

[Chad Vossen]

mag is like calcium's little brother. it is used up while calcium is being used. thats where it is going.

did this hit the question right?

i also test the mag in new saltwater, and make sure to raise it.

[coldwaterreefer]

you have to add mag also

[David Grigor]

Magnesium should deplete at a rate or 1-3% ( slightly varies per coral ) of your Calcium rate.

My personal hunch is that your not taking in account what the Mg ppm of your fresly mixed saltwater. The magnesium can be getting lower every time you do a water change if the salt mixes to a lower Magnesium ppm than your tank started.

So for sure check your Magnesium level in your salt mix and adjust that parameter BEFORE you do a water change.

Then see how it goes.

[lost in it all]

I guess I should have been a little more clear.... and side note I did take into account the newly mixed saltwater RC and I thought the levels were close but did not write them down anywhere I will mix up a batch today and check again.. here are the directions from BRS and were I am having the problem.

Once the dose is dialed in continue daily dosing until the gallon jugs of Calcium and Alkalinity are finished. At this point it is time to dose 20oz of the Magnesium solution. This can be done entirely in one dose just remember to add slowly to a high flow area of the tank.

so that out there I will check the new saltwater but it still should not be near 200 oz of mag needed only 20 oz (+amount needed to bring up nsw maybe 15oz) and the calcium gallon is not gone yet.

[David Grigor]

Pretty much the only explanation I can think of. Providing your Mag. level was correct before you started. 1-3% of Calcium should be the normal usage.

If the salt is not low, either your testing is off or your precipitating somehow. That's pretty much all it could be. How to determine if precipitating would be anyones guess from just a thread.

I wouldn't dwell on it much. It is what it is and add whatever amount is necessary to keep it in check.

[dobbs]

I wouldn't dwell on it much. It is what it is and add whatever amount is necessary to keep it in check.

DG,

Shouldn't he make sure that his test kit is correct before adding more Mag? I thought that I read somewhere that too much mag can harm some types of inverts???

[David Grigor]

For sure. Testing being off can for sure be a concern and double checked / verified. Having a local reefer bring there test kit and administer the test is good way to go.

100ppm per day is the recommends max.

I'd personally go slower. If Mg levels in the show tank are low but not dangerously low, I prefer to bump up my water change values of my salt and not directly dosing until it's where you want it to be. This way it's spread over weeks to months.

[David Grigor]

Another possible explaination would be to be sure your salinity is the same as it was when the first test was performed.

1.0264 to 1.024 can have an 100+ ppm effect on mg levels.

For example: 1300 ppm reading at 1.0264 is the same as 1182 ppm at 1.024.

[lost in it all]

thanks David I dumped and cleaned my mixing trash can so I could start over and the mag was about 100ppm lower in the RC then what I thought so I will start there and see what happens.