Backyard Aquaponics
A place to discuss aquaponics

The water in our tank is dark green. We have wrapped the tank to prevent sunlight, but the water remains dark green. Any advice?

Folks will really need more information on your system before any advice can be offered.
Size of system?
Number of Fish?
Indoor or outdoor?
Type(s) of filtration?
Water test results?
History of the system?
Got photos?

Water in tank is dark green due to algae which is further of many types so you need to protect water from algae and it is better to have either some sort of chemical which must be safer to human or you may have aquatic animal which can eat away those algae. Thanks

your water is full of free floating single celled algae or phytoplankton.
for fish breeders that is actually a wonderful thing, its a natural food for fish both directly and indirectly.

buuuut if you want it the water to be clear you could put on some screen to shade the water, limiting sunlight will usually kill off the algae... also be sure not to feed the fish too much, since every waste products the fish excrete will get eaten by the algae... so you may also need a larger filter system to deal with the excess nutrients.

Willlo, what type of fish are you raising? If it is tilapia, I you'll say just hold off the feed for a little while, and allow the tilapia to feed off of it. Algae is actually tilapia's preferred food source. People try all kinds of things aside from fish to control algae, from barley hay to UV filters. The most effective control people have found outside of algae eating fish is to add more gravel beds. The algae clings to the gravel, and dies. As algae dies, it releases a hormone that kills off more algae.