Sump Work - How long offline?

I just noticed that the egg crate which supports my bio balls fell on one side and roughly 15% of the balls are submerged completely. I will be taking the sump "offline" in order to re-install and silicone supports, as well as fabricate a lid to prevent evaporation --the compartment has gotten quite damp and the door has become difficult to close at times. I figure I may as well get all the work done while I'm in there... I plan to do all of this by next Friday as I just completed a 25% water change.


Question:
How log can I take the pump/filter system offline in order to work on it? I have two 1,000gph powerheads that will remain online. My tank is a 72 mixed reef. 8 corals and 6 small fish (hippo, clown x 2, firefish x 2, watchman goby).

 

I would think a few days to do major maintenance, such as this, would be alright. Considering the amount of water flow in the DT.

 

So keeping nothing on but the powerheads with a little ripple at the surface will be adequate? I was only planning on 5-6 hours, but you never know when you start pulling that crap out!

 

Well that is 2,00gph through the DT. I see no problem. Especially if it's only for one day.

 

I had my sump offline for about 2 weeks, the only negative consequence was an outbreak of hair algae thats almost completely gone now that the sump is up and running again.