# Using Water Lettuce Against Green Water



## RiverRocks (Jan 21, 2014)

Recently, while on an 8 day vacation, I left my 80 gallon "dirted" tank in the care of my two teenage daughters. When I returned, the tank was infested with algae, as shown in the attached photo. Someone, apparently, got overzealous with feeding. The first thing I did was drain the tank down to about 20% and clean every thing in the tank, including the glass, by hand. It looked good, immediately after the new water was added, but it only took about 3 days for the water to green up again. After a week, I could hardly see the fish anymore! 

In search of a solution, I went to Diana Walstad's book, and re-read the chapter on algae control (chapter 10). In that chapter, she suggests using water lettuce and other floating plants, such as duck weed, against green water. I put two water lettuces into my tank along with a handful of duck weed. The duck weed was completely eaten by my adult moonlight gourami (who knew they'd do that) but the water lettuce, as Walstad describes, developed bushy roots and started growing. After I put the floating plants in, I did two water changes (50%, at about a week apart) and reduced the lighting to about half the usual value. The second photo shows the tank as it looks now, about 4 weeks later. I've had this tank for over a year. I've never seen the water so clear!


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## Michael (Jul 20, 2010)

RiverRocks, welcome to APC!

Floating plants are a great tool for controlling some types of algae. Water lettuce is prohibited in some states, but as far as I know frog bit is legal everywhere in the USA. (Please correct me if I'm wrong!) I keep some floaters going all the time, just in case I need some. The nice thing is that only a few are needed; they will multiply to effective levels quickly if they are going to work at all.


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