"Flag tails really that good at cleaning algae? If only they weren't so ugly, lol...."
In my experience, flagtails are wonderful at keeping surfaces algae free, except for well-set green spot algae such as the interface of bottom and front/side panels. Even above that interface, my flagtail does not do much for green spot algae but it is amazing on other types + general debris. Again, in my experience no fish or snail would clean that interface and in acrylic tanks the most effective way is the old credit card edge (equivalent to the plastic flat blade piece mentioned here).
I am surprised that the green scrubby pads (such as for dishwashing) have not been mentioned much in this thread. I find them fantastic on my only acrylic tank, as well as in several glass tanks, despite requiring putting my whole arm in the tank. Unless they catch sand grains, they do not scratch acrylic, as the material is softer than the acrylic (remember the Moh's hardness scale from science class? - Only harder materials can scratch softer materials)
I guess the ugliness of flagtails is a personal thing but I find it hard to believe...
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