since mine broke i hanvt been able to get another one (cascade 80, i lost the impeller)
so how long is it safe to keep the tank without a filter? is there anything i can do to prolong the time? maybe keep the insert in the tank for a couple mins?
just go get a cheap filter that will at least clear up the water. you can get them for about 12 bucks. thats what i did for now. i got a tetra whisper 2-10i internal filter. its great but the only problem is that if you have a pleco they will want to hide in it so what ive done is when mine goes in there i poke him with the net handle and he gets out. after like 3 tries of that hes found a new home behind the heater.
If you are willing to make major, regular water changes, the tank would be fine indefinately - remember there have been tanks far longer than filters - even the Egyptians kept fish in containers as pets!