Quarantine Tank Help

[mikeclarke]

Hi there,

In the summer I upgraded my 20gal tank to a 100gal+50gal sump system. My 20gal had been a FOWLR with no skimmer, no UV... just basic. It went really well which is why I was excited to upgrade. I removed all but one little tiny piece of LR and all the live stock to the big tank. I left about 1cm of sand at the bottom of the QT and bought a big pirate ship as I couldn't convince my wife to leave pieces of PVC in a bare bottom tank when it is in the den off the kitchen. I've been taking 10gal of water out of the QT tank almost weekly (even when there is nothing in it) and replacing it with water from the big system. Then I use new make-up water in the big system.

A month or two ago I got a kole eye tang, yellow sailfin tang, and a copperbanded butterfly. I had them in the QT tank and seemed to be doing well. After a week both tangs died. I tested the water and the PH was really low. Like 6.4 or something. I can't remember. All I dosed was herbtana and artimiss as everyone looked good until they were at the bottom. I took the CBB and acclimated to the big tank and he has been thriving. He eats all the mysis and cyclops eeze that I give him.

So I'd like to get a tang for the 6' 100 gallon but I don't want to waste my money. How do I keep a QT tank looking nice but keeping the water quality high?