algae

Question
Mick, I have a twenty gallon tank with numerous hatchlings >6 mos old. I have UVB and UVA lighting which stays on for about 12 hours/day.  I feed them in a separate container once per day.  Compact 10.0 Reptisun for Uvb and standard 50 w Reptisun heat lamp.  Substrate is natural stone around 1 cm in diameter. Filtration is 501 Fluval.  Numerous aquatic plants for browsing. All feeding well and growing.  Just recently have had string like algae growth on walls of tank. Question:  Can I use standard algaecide tablets or will this harm turtles?  Turtle size is approximately 3 inches from snout to tail.  Tank is placed next to a window of S.E. direction.  It is winter here in Michigan and from past experience, my hatchlings seem to do better with natural light even though through a window. Thanks, Wayne

Answer
I'd have to know what chemical is in the algaecide, but I would tend to stay away from introduction of chemical plant killing toxins in the tank where edible plants are consumed and hatchlings are living. Algae is not all bad. It deals with a fair amount of toxins in the tank. This probably indicates your tank is over crowded, filtration inadequate, or perhaps you should reduce UV expose, since algae usually blooms from this.