Posted: Fri Mar 03, 2017 4:02 pm Re: Nitrate removal.
Comes down to your state laws , some plants will be an invasive species and will not be available even online to ship to you. Even what some think are better at removing nitrites will only have an small effect on your tank. The type of rocks if any , soil media for rooted plants , decorations all affect the water. Most turtles as they get older ( around 2or3 +) should have about 75% of there diet veggie ! Could be hard for the best plant to keep up with. I have a 70 gallon plant tank outside just to keep up with Piggley 5" RES male on top of what's in his 150 gallon home.
Duckweed first but messy // annoying , frogbit , hornwort , water sprite are others with less maintenance. Most floating plants do better than rooted. BUT the massive amount to record any change in parameters ... overwhelming in a regular tank. Have seen very shallow 3-5" tanks with a very large surface area 5' or more make some difference on the readings but will be no good for your turtle. In my time aquaponics works better with fish , just my opinion. Good luck.