Seachem phosguard is very effective at removing phosphate.  The problem is that it is aluminium-based (as opposed to iron-based like GFO) and there are reports of corals reacting adversely to it.  You can mail-order GFO in bulk from several sources including one of the site sponsors, bulkreefsupply.com. 
		
	
		
		
		
		
		
	
		
		
	
	
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