EI Fertilization Method

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Original poster, but anyone else I guess. I'm not looking to buy in lbs, since I only have a 20g tank, so I'm looking to see if there's cheap alternatives. The link to aquariumfertilizers.com (from John N's article) is down, but I'm assuming 1lb. bags of these are pretty expensive. Anyone recommend getting them from homedepot or plant stores, or would the be more expensive?
 
I bought those at a Hydroponics store. The local fish forum said that KNO3 is available at a hydroponics store near my house (a few blocks away). They sell them for $4 for a lb of each KNO3 and K2SO4, and $5 for a lb of KH2PO4.
 
Original poster, but anyone else I guess. I'm not looking to buy in lbs, since I only have a 20g tank, so I'm looking to see if there's cheap alternatives. The link to aquariumfertilizers.com (from John N's article) is down, but I'm assuming 1lb. bags of these are pretty expensive. Anyone recommend getting them from homedepot or plant stores, or would the be more expensive?

Here is the most reasonable source;
http://www.bestaquariumregulator.com/ferts.html
really cheap if you ask me.
 
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