IMO it is unreasonable to set the bar at introducing 0 nitrates into your system. You are going to get them - from food, poop, tons of sources. one way of getting rid of nitrates is via algae growth (as you are experiencing). But like everything else in nature, this needs to be kept in check. That is where your CuC comes in. They eat the algae. (and the CuC does not tend to grow out of control like GHA ) The goal is to strike a balance between how fast your algae grows and how fast your CuC eats it. This is primarily controlled by CuC population control. As it turns out, John Maloney is almost magically gifted at predicting this balance. It is really quite amazing how many folks can attest to that. In much the same way your tank will forever cycle invisibly to you, the cycle of nitrates -> algae -> full CuC tummies should be invisible to you other than a living CuC (w/o die-off); that is to say you should not ever notice the algae grow. That is the goal... some tanks seem to really be *in the zone* on this and others are not. I just felt like typing and thinking on that... just my opinions on balance in nature and mimicking that in a tank.