It was a long, hard 2-year struggle. Apparently we have some pretty aggressive algae species around here. I learned this the hard way after the Pond had a similar problem, and trying to run too much light on this tank. A CO2 injection system and an adjustable-intensity light finally got things under control. It was so bad by last spring that I needed to shift the guppies to the goldfish tank, break this one down completely, clean and re-start it.
The solution was a combination of CO2 injection and GREATLY reduced lighting. Most decorative aquatic plants can’t get enough CO2 for efficient photosynthesis from household aquarium water. A few bits and pieces with a tank of CO2 solves that problem nicely.
I wanted this tank to be brightly lit because it is planted and forms the centerpiece in a dark basement. But no amount of time reduction was enough to slow algae growth with the 60″ LED I initially purchased for it years ago. This 165-watt dimm-able full-spectrum model leaves the ends of the tank almost dark and at about 40% intensity for 10 hours/day seems to do the trick. These guys have the best habitat in the whole zoo. Plants filter, buffer and oxygenate the water chemistry while Purigen organic waste control absorbs any toxic residue. It’s a nice Guppy life, but then they go upstairs to be eaten by the Firemouths after growing big enough. I’m pretty sure this water would be safe to drink.