Murky Water

Question
I have a 65 gallon tank that's been up for about four months. Ten fish - some danios, a guppy, some mollies, some others. The fish are happy and the chemistry's been good, so I have been reluctant to do much to it.

It's been getting some brown algae on the bottom, so I figured I'd vac up some of it and change out about 20 percent of the water.

Now, I don't know what I was thinking, but I decided to rinse out the underwater filter. As I was lifting it out, I remembered - that sucker drips something awful. So when I pulled it out of the water, all of the water that was IN the filter poured out into the tank - along with all the muck and effluvia and God knows what else was trapped inside the filter.

So I took a bit more water out - not much, total less than 1/4 - and refreshed. Six hours later, the water is still very dark and murky. I can't see through the tank.

Adding to the complications, I'm leaving town for three weeks - so a daily ten-twenty percent water change isn't possible. (My wife will be home to feed the fish and add water, but actually setting up the siphon and refreshing is beyond her scope).

So:
1) I figure I'll swap out about 40 - 50 percent of the water before I go. How bad is that going to be for the fish?

2) With half-fresh, half-gnarly water, will any of the fish make it? Or are they basically choking to death in a septic tank?

Which is going to be worse - the shock of changing the water? Or the toxicity of what was in the filter?

Thanks!

Answer
RJB,

Sorry to hear of the problem you are having. I would continue to do the water changes everyday. I do not think that a large scale water change of even 80%  will do the fish any more harm. The sooner you get the mucky stuff out the sooner the fish will recoop from it. Make sure you condition the new water and that its the same temp as the tank water. I think you will be fine with the water changes and that it will just take a little time. However, if any of the fish start to look like they are starting to suffer in any way, remove them from that tank right away and place them in a QT.

I hope this helps and if you have any more questions, don't hesitate to ask.