What is the Ksp of Al(OH)3?
Let me add to the confusion: 


https://books.google.de/books?id=imBzjH6SHi8C&amp;pg=PA303&amp;lpg=PA303&amp;dq=solubility+product+constant+aluminum+hydroxide&amp;source=bl&amp;ots=jXoPiVihnF&amp;sig=eSK8saszXshTXVEKGOlThUiKVr0&amp;hl=de&amp;sa=X&amp;ei=Xl5TVcepDuj_ywOXmYDQBA&amp;ved=0CG8Q6AEwCTgK#v=onepage&amp;q=solubility%20product%20constant%20aluminum%20hydroxide&amp;f=false
$2\times10^{-32}$
http://faculty.ncc.edu/LinkClick.aspx?fileticket=smTKdcQlPY4%3D&amp;tabid=1903
$1.8\times10^{-33}$
http://www.austincc.edu/dlyon/gen_chem_1_summer04/Chapter%2020%20solubiliity%20product%20f08.pdf
$1.9\times 10^{-33}$  
http://www.csudh.edu/oliver/chemdata/data-ksp.htm
$4.6\times10^{-33}$  
http://www.periodni.com/solubility_product_constants.html
$3\times 10^{-34}$  
https://users.stlcc.edu/gkrishnan/ksptable.html
$3\times 10^{-34}$


Usually I'd first have a look at the CRC Handbook of Chemistry and Physics. Unfortunately, I couldn't find the data for aluminium hydroxide.