Hard and cheap will mean dosing according to the Estimative Index by Tom Barr, and using chemicals like potassium nitrate and potassium phosphate.
The hard part is actually understanding the above article. There's alot of measurement and science to it, but once you get it clear it's damn simple.
Perhaps you might want to read the above article once or twice, and search around abit regarding the estimative index.
A summary of the article will be: Dose KNO3 and KH2PO4 along with traces to account for all nutrients plants need. Excess is acceptable, and nutrients like nitrate are prevented from building up by 50% weekly water changes. CO2's importance is greatly emphasised.
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