Will aluminium lower alk?

[Sawen]

I know GFO will lower alk.

But will aluminium based phosphate resins lower alk as well?

 

[bertoni]

I think that they can, but possibly not to the same extent. Phosphate helps prevent precipitation in the same way that magnesium does, so removing it will increase precipitation, if only by a tiny amount in the tank as a whole. I am not sure that aluminum oxide will show the pH increase effect of GFO, though. This article has some information about GFO and precipitation:

http://reefkeeping.com/issues/2004-11/rhf/index.htm

 

[Tat2demon]

Is aluminum oxide toxic in saltwater like aluminum is?

 

[disc1]

Is aluminum oxide toxic in saltwater like aluminum is?

Alumina isn't soluble enough to get into the water.

 

[Randy Holmes-Farley]

I do think that aluminum oxide can dissolve enough to be potentially irritating to corals. I show experimental results for both aluminum oxide and soluble aluminum ion in the article linked below.

In any case, it does appear that aluminum oxide can do something to the water that can irritate corals, and whether that is small particles of aluminum oxide, or actual dissolve aluminum ions, there can be some effect.

Aluminum and aluminum-based phosphate binders
http://www.advancedaquarist.com/issues/july2003/chem.htm