I think it helps a little I dont know how much. When I started pothos on my 75 I was kind of checking it to see if I could see a difference and at first there was nothing but once it started growing I did see that instead of my nitrates hitting 40+ between water changes (weekly) it would go a little more then 20. I tried to keep everything constant during that time period. I think it does a little but its not a miracle cure and how much you have growing also matters. Currently I'm at about the same spot nitrates around 30 at wc time after wc around 5. Also on the new system I was doing a drip and while it does stabilize everything I was always around 20-30 ppm nitrate it never went below that. I was changing around 60gpd. I've switched to just doing a large water change once a week now and I have a little more fluctuation in the parameters but I'm using less water over all. I still have the drip set up but at about 5gpd just for evap mostly. I'm heavily stocked, I feed a lot, but I only feed every other day sometimes skipping 2 days. Except for the growouts in the pothos tank I feed them heavily almost every day. The whole system is linked. I have other plants in the tanks and have so so luck with them. I dose flourish 3 times a week.
So is the pothos working I'm going to say its a deffinate maybe