i'm going on my own experience.
i first heard of this means of eliminating greenwater problems from another forum. it sounded questionable to me there.
and within a few weeks later as i was nice and proud of my greenwater, i bought a clam, happy he'd have food, ... and within a few days my greenwater cleared up, ... my clam died of starvation afterwards, and i was rather upset about the whole thing. ...
i don't know how long as i really didn't time it to see how long it would take to crash ... was not intending to let it crash, i wanted to sustain it.
so the above 2-4 weeks or whatever i mentioned for it to crash, is an estimate. it may happen sooner, i don't think it will take longer.
it does get thick/dark enough you can only see a few inches into the tank clearly, and a few more inches to know there's stuff there, ... but it's harder to tell, ... but not seeing though to the back.
...
again going back to what was mentioned in the other forum, ... once the greenwater crashes, they mentioned it's like your tanks gets an immunity to it, ... and from my experience this is the case as well, ... i have tried (at first) to continously add more greenwater to the tank, and within a few days it clears up again, ... i gave up on this for several months, (i think about 3) tried again from the culture i was keeping) and ... well this time it took a week before the water was clear again, ... and trying again within a few days the water was clear.
my next estimate, i'm hoping it will be good to start again within 6 months to maintain a culture.
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but from my experience and others experiences that knew before me, ... ignoring it is one way to clear up greenwater, ... great if you don't want it in your tank, ... but it really sucks if you do want it.
there's a few critters you can add to your tank that having greenwater will keep them alive (it's food) that you can't do without it.
clams & freshwater sponges are a couple of them, ... live food like zooplankton, ... those are the ones that have caught my attention, ... but time will tell ... i can't consider them again in the tank till i can get greenwater going in the tank again
