Chris, You wont have a "crash" but in theory you will lower your DO somewhat. Since your pond is shallow it can pick up O2 with some wind / wave action.Aquashade is blue and yellow acid The yellow is slight perhaps 2.39 or 2.79 % what yellow and blue can give you a greenish (antifreeze) look at times even though it pours out very blue.Usually with chara and w. grass you have little FA as the competition for nutrients is won by the Chara, often times eliminating it brings on more FA. Shallow small ponds take the most management skills so hang in there. Bruce your right"unbelievably busy"