I have a 20-gallon fresh; for water changes, I simply use 1-gallon jugs of tap water, dechlorinated with TopFin dechlorinator (no fancy ingredients -- 2 drops per gallon). When attempting to remove a couple of cory fry to re-home, my fish seemed to get stressed. All I had on hand was Api Stresscoat, so even though no dechlorinator was needed, I added about 15 ml. to the tank. Question: is there ever TOO MUCH dechlorinator? (I have since read about Seachem Stress Guard. Do you recommend keeping that on hand for these occasions?) If using Stresscoat to dechlorinate at water change: the bottle says 5 ml per 10 gallons and say I'm doing just a 4-gallon water change) is it okay to add the 5 ml? If so, is it okay to add it to just one jug first and then add the other three (which would have no dechlorinator in them)? Or should I cut the amount to about 2 ml? (....sorta confused about dechlorinators....) I've also read that Seachem Prime is the best water conditioner. True? Thank you very much for your answers and suggestions.