Mg in Topoff Water?

[holy carp]

I've got my 2 BRS dosers set up for my 2 part, but I've been noticing lately that my Mg needs about 30ml per week or it will drop below 1200.

 

So my question is if Mg (I'm using ESV) is stable in RODI water for topoff or if it will settle out. Will it affect pumps (I've got my topoff running a timed aqualifter). My evaporation seems pretty consistent at around 1.5-2 gallons per week, so I was thinking of just adding 60-90ml into my 5 gallon topoff bucket. From what I've read, Mg is pretty forgiving anywhere in the 1200 to 1400 range, so I was hoping this would be a nice alternative to another dosing pump.

 

Are they any reasons why that isn't a good idea?

Thanks.

[seabass]

There's no need to dose magnesium in ATO water; just dump it into your display versus the top off water.

 

Watch how they dose magnesium in this video:

[Mikeymikemike]

I just dry dose magnesium. It will dissolve quickly.

[seabass]

I just dry dose magnesium. It will dissolve quickly.

You might get away with that in a sump, but I would still dissolve in RO/DI first.

[holy carp]

I was actually thinking in terms of vacation, since I'll be away for 2 weeks for the first time since having a tank. The dosers and the feeder should do fine, but I normally do weekly water changes, so I'm not really sure how much mg might drop while I'm away...

[seabass]

The thing about magnesium, is that stability isn't as important as calcium, or certainly alkalinity (so a two week period should be fine).

 

Here is the section on dosing magnesium. You can compute the consumption rate, so you could easily dose before and after your trip without need of automating magnesium supplementation.

[holy carp]

Thanks, seabass. I'll do that and just dose it up about an extra weeks worth (1/2 the trip) before I leave so the average should stay pretty normal.