hypo and ich

[drtash]

Hello
My 220 gal came down with ich Dec 18th. It have been in hypo since that day. salinity constant at 1.009. Last week I saw NO ich on any of my fish (4 weeks into treatment). I put back the LR into my DT and now Ich is appearing.
Question #1 How long can the salinity be at 1.009 without hurting the fish?
My tank is still at 1.009 in my 220 gal and with my live rock. Why did the ich come back. The LR was originally placed into another tank for 4 weeks. The fish were Quarantined for 4 weeks.
Suggestions

 

[sepulatian]

Why did you move the rock back in? The life on the rock will die at hypo-saline levels. Get it out of there. You have been treating your fish for four weeks, at a constant 1.009, and the ich was just visibly gone last week? Something is not right here. What are you using to measure the SG?

 

[gmann1139]

You took a 220g from normal to hyposalinity in one day? Wow, That's a lot of water changes, not to mention tough on the fish.