Who do you order it from? When I looked at a couple of the online vendors, it was insane with the cost of shipping.seriously, it makes a difference! try the small bag first, and then when you see the difference, get the 5 gallon jug! order from the vet online, and you'll save money with both sizes. I also have air coming from outside, then to scrubber, then to skimmer and I have to back mine off! it goes to 8.5!! which, I am ok with to a point...but I can tell you, my coral growth has been stupid fast!