Help!! Help with biocube.

Ok.

I don't have pics, but at night most of the rocks get smaller "tentacles" that come out from them now, that I never noticed before. Is this normal?...or a byproduct of having phosphates in the tank that will also go away?

 

I'd like to get my mag up to 1350 and the magnesium calculator at seachem says to get it there, it will take 42grams in my 29g biocube (to get it up 45 points to 350) of their product. It also says not to dose more than 25gms per day...5 tablespoons.

The total amount the calculator says to dose is 8.5 tablespoons to go up 45 points.

I'm gonna do 5 tablespoons today then the other 3.5 tomorrow night at the same time.

here's my question...when I'm figuring the dosages for additives, do you use total gallons the tank holds, or try to figure how much water there is after displacement (rock work, sand, etc)

 

This is the first time I've ever dosed anything in the tank over 1 tablespoon in a 24hr period. I guess I just figured that if those are acceptable amounts without stressing/harming anything, it would be easier to get the magnesium there a little quicker.