Tub pond - everything dying

Question
I am truly a beginner at this.  I purchased a 40 gallon tub that I have on my back, very sunny patio.  In the tub I had 2 small koi, water lettuce, water hyacinth, 2 oxegenators, a dwarf lily, cattail and a couple other marginals.  I also have a small aerator.  The pond was doing great.  I left for a short (4 day) vacation and now my pond looks horrible. One fish died. The water hyacinth is brown.  The water lettuce white. Some of the leaves on the lily are brown also.  Do you have any idea what could have happened?  Thanks so much. Kara

Answer
Hello Kara!
It is hard to tell, but here are some ideas:
Koi cannot survive in a tub, they need much more water than that and they are very, very sensitive to sudden temperature changes which can happen quickly in such a small container. Goldfish are much better suited to that environment.
The water lettuce is probably just bleached from the sun. Water Lettuce prefers shade.
Water Hyacinth usually turn brown when the pH of the water is too high.
Water Lilies do not like to get splashed with water. Make sure you aerator does not spray water on to their leaves.
Brigitte
www.pondmarket.com