[sphelps]

Yeah I'm going to continue down the road assuming we're talking about hypo for obvious reasons. For me the problem I find is it's not overly easy to maintain a hypo tank. Ideally you want to maintain a cycled tank at 1.009 SG which is pretty easy but it gets complicated when you need to maintain a higher pH around 7.8, a constant pH monitor is key to this IME. You also need a refractometer that's accurate in that range which can be hard to confirm, although I think most aren't an issue, but if SG is too low fish will die and if SG is too high parasites will survive.

The next issue relates to raising the salinity back up to normal levels which if done in the hypo tank it may effect the cycle (I got ammonia spike doing this but I see others not mentioning any issues) and you risk releasing surviving parasites as well. Plus if you use a decent size QT like I do (55 gallons) raising and lowering the salinity is pretty wasteful and can be costly on salt. Also the whole procedure of holding fish for 4 weeks at hypo then raising salinity and holding for another 4 weeks is just too painful for me personally, it's going to be stressful for a fish and lot of work which 9 times out of 10 wasn't necessary in the first place.

Currently I'm now using two tanks, one hypo cycled and always maintained at 1.009 which in theory means ich can never reach Theront stage (attach to fish). The other cycled and maintained at natural seawater levels. I'm going to be adding an acclimation station between the two so I can preform tank transfers as necessarily. I find acclimating fish to hypo can be done fairly quickly (over a few hours) and the going the other way a little slower (12 hours). I personally think acclimating over a week is overkill but to each their own.

With the two tanks fish potentially effected with ich only need to stay in hypo tank for 8 days to insure the ich has fallen off the fish, they can then be transferred to the other tank and monitored as long as necessary to confirm fish is healthy and no other diseases are present. Cuts off at least 3 weeks, significantly more if it's only ich you're concerned with. The hypo tank can be used for it's other benefits as well plus with the two tanks I'm not limited to purchasing fish once every 2-3 months.