I haven't used citric acid in a while, but I think curlyserf got it right 1/4 t to 1 c water.
Forgot to add, that those are the only citric rinses that I know. I often wonder if it's necessary, if your products have a pH of 4.5?? They go on your hair and should restore pH shouldn't they??
3a (Corkicelli), highlighted, fine, low porosity
modified CG, since April '07
CG since 3/11/08
HGs: Anything Sevi; Curly Kinks Satin Roots, Curlycue ReNew and Coil Jam; homemade FSG and okra gel; soap bars; UFD Curly Magic; Botanical Spirits Jellies, CJ Repair Me