In the 2/3 ac pond, as long as you have the correct dosage, it wouldn't matter. The biggest thing is you have to watch the water pH that you are using to mix it with in the tank.

Surface Application - Mix .75-1.5 Ounce of Propeller with 1 gallon of water for every 1/8 acre (5,456 feet). So you would need to use 7.92 ounces at max dose.

Subsurface Application - Mix 2.2-4.4 Ounces of Propeller with 1 gallon of water for every 1/8 acre (5,456 feet) per 1' average depth. i.e. 1/8 acre with 3' average depth would require 12 Ounces (4 Ounces x 3) You would need to use 209 ounces at max dose.

www.hoosierpondpros.com

[Linked Image from lh6.ggpht.com]
http://www.pondboss.com/subscribe.asp?c=4
3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).