Plans to rid ich, need advice

[asylumdown]

Alright, after that little hiccup that cost me most of my corals, I got back in to the tang game, and while I knew my tank was never 'ich free', I didn't expect the explosion that bringing in these two tangs would cause. I'm worried for their survival at this point (the tangs), but I figure if I'm going in for a penny, I'm going in for the whole damn pound.

I knew my tank had ich in it pretty early on, but since it never seemed to bother anyone beyond a few pesky spots that went away after a day or so, the effort of getting everyone out for treatment never seemed worth it. I added a powder blue and a purple tang this week, and BAM! Now fish that never seemed to be bothered by it are flashing and scratching. The purple tang will probably get over it himseld, but the powder blue won't survive without intervention, so here's my plan:

I don't think putting all my fish in the 40 gallon breeder I have with a crappy canister filter is going to work. They'll die from the cycle, crowding, and inevitable water quality issues long before the display is ich free, so instead I'm going to put my unorthodox sump to good use.

The sump is 4 chambered, with a 20 gallon (approx) skimmer chamber, a 15 gallon (approx) 'frag chamber' (that is currently being used as a place for extra live rock), a 50 gallon "water change chamber" and a 15ish gallon return chamber. The sump is designed so that during water chambers, I can divert the flow directly in to the return chamber, bypassing the first three chambers completely. Normally, I would then use a pump with a hose pointed to a drain to empty the 50 gallon WC chamber, then fill that chamber back up with R/O water, mix salt, then bring the whole sump back online again. To do the ich treatment, I'm going to spread my fish out between the water change chamber and the skimmer chamber, divert the flow so that my display is bypassing most of the sump, and then use the pump that would normally drain the water change chamber as a 'return pump' for my new little isolated system, pumping water from the water change chamber back in to the skimmer chamber. Then I'll drop the salinity in that isolated sump system down to 1.010 and leave my display tank fallow for 8 weeks.

I hope this will be a less stressful process for the fish, as they will have 95ish gallons of system volume, still have a functioning protein skimmer, two heaters, and about 50 pounds of cycled rock to filter the water for them. The auto-doser is also already set up above the frag chamber with a reservoir of carbonate solution to keep the pH up. My display tank will be fishless so it won't need the skimmer, and it will still have it's own heaters (in the return chamber) and the auto-top off system. The only thing I'll need to do manually is add R/O water to the quarantine part of the sump to keep it level, but at this point that's as simple as flipping a switch, since the pump that brings it up for water changes pumps in to the water change chamber anyway.

The only thing I'm concerned about is that the frag chamber with all the rock in it also has about 3 inches of sand for pods to breed in away from the hungry searching of my wrasses. I'm sure there will be a lot of die off from the hypo, but I don't know how much of an issue this will be.

Does anyone have any input, advice, or sees an issue I haven't thought of? Should I take the reactor with GFO that's currently in the water change chamber offline for this, or should I leave it running in the hypo treatment? What about my biopellet reactor? Currently it draws and returns water from the skimmer chamber, but sits in the water change chamber, both of which will be in hypo for 8 weeks. Will the bacteria in it survive the treatment (and help maintain water quality in the quarantine system) or would I be better off moving it's inputs and outputs so that it's still part of the display system?

Also, anyone have any advice on how to get 16 fish out of a 250 gallon tank in less than 2 hours?