Just won't go away

[E.Y.]

I haven't....   I added a new HOB filter loaded with carbon.   It helped for most of last week.  I came back into the office today and it was getting cloudy again.

[cranialdisturbance]

Are you using an automatic feeder on the weekends?

[E.Y.]

I am not. 

[cranialdisturbance]

I have not used Aqueon water conditioner but I did happen to be reading the back of a free packet included on one of my tanks yesterday.  I believe the dosage is 5ml per 10g where Prime is 1ml per 10g.  Perhaps there are some other additives in there which are causing issues with your water chemistry. 

I know years ago I made a brief switch from Stress Coat to AP's "new and improved" dechlorinator, Ammo Lock.  That was like summoning the grim reaper.  Cloudiness followed by whole tanks of fish dying. 

[cranialdisturbance]

Also, check out this article about using a gravel vac on tanks with sand for substrate.

http://www.aquaworldaquarium.com/Articles/TonyGriffitts/silent_killer.htm

[E.Y.]

Thank you for all the suggestions and advice.  I have switched back to only using prime.  I noticed that after adding the filter full of carbon I was able to go a week without the cloudiness.  I added the water clarifier yesterday, and it did its job in only a couple hours. 

I noticed that today, the tank is still clear so, as of now, it seems to be subsiding somewhat.  At least, I'm going longer in between periods of cloudiness...