The previous time I was in the hobby, I used it by the bottle. I even bought the same chemical in bulk because the little aquarium bottles were costing me so much. All that I can say is that I lost lots of fish and never had a stable pH in my tanks. Now I take tap water and treat it with dechlorinator, that is it. No pH adjusting chemicals ever in my tanks and very few fish deaths. If I have a tank full of fish that like very soft water, I mix some RO with tap water to get the right hardness but still pay no attention to pH. My fish thrive in most situations unless I get a soft water fish from a place that babies them and they don't warn me so that I can bring them up gradually to my water conditions.