You are correct, Don. Dechlorinated water has nothing to protect it from outside bacteria.
Given that you are immediately removing the disinfectant with Prime and then leaving 50% of the water with each daily change I would be concerned that the cloudiness is actually biologic. Regardless the best approach is indeed to age/aerate/heat x 24 then add the prime to the display tank at the time of the WC and treat the total DT volume. I would also dispose of the cloudy water by doing a 100% WC in the aging tank, the chloramine from the tap will persist well beyond 24 hours and inhibit any further growth if indeed your AT is colonized with something. Alternatively after a 100% AT change you can add the prime to the AT just prior to a WC and only treat the lower volume but then you should only age 15 gallons or whatever you want your WC volume to be, but not more such that you are replacing 100 % of the water in the AT . Saves a little prime if you care.
You are correct, Don. Dechlorinated water has nothing to protect it from outside bacteria.
Mama Bear
When in doubt throw it out.
Cliff
The bacteria causing the cloudiness, if it is indeed bacteria, is probably harmless.
On the other hand, there's much more bacteria in nutrient-rich aquarium water and it's potentially pathogenic bacteria.
I learned a lot from you guys, thanks a lot!
If I may add a slight twist to the OP’s question. If tap water contains only chlorine, which I understand dissipates within a few hours of aeration. Any concern about aging this de-chlorinated water for 24-48 hours?
No not at all. The ph stability may still be going on. I had a ph pen I kept calibrated so I could easily take ph reading at refill. Then 24hr later then 48hrs just to see. Sometimes depending on what the water company was using to buffer the water could take longer to stabilize. So just to see take ph readings you may find out more information for your case.
Dave, if you are aging (x) amount of water and then only pulling out 1/2 (x) 24 hours later then your point is a good one presuming only chlorine is being used. Having said that the risk of colonization would be less because Pakho was adding Prime immediately on adding more water to the aging tank, eliminating chlorine and chloramine immediately. With heating and aeration your chlorine half life would be much less than 24 hours but I am unsure how long it would persist and have some residual antibacterial action. Bottom line avoid the risk and age only the amount of water you intend to use. I do agree with Megalodon that whatever grows is likely non-pathogenic to fish but why take the risk. Also would probably be aerobic, so you are aerating your water to provide O2 to a pest. Why bother.