+1 to what everyone else mentioned. Judging from your past posts and setup my first guess is gonna be the HOB filter is the culprit. If you have not taken it off and completely cleaned it and replaced all media I would alomost certainly say that is the cause of the smell. You mentioned small particles of food being uneaten by the chromis. As time goes on that food is going to rot in your tank or in the filter. If you are using filter floss in the HOB, you're gonna want to replace that every 2 to 3 days and if you are using a sponge, clean or replace that every 3 days as well. If you are doing weekly water changes a though cleaning of the filter should be part of that process (minimum cleaning every 2 weeks).
The next suggestion would be to run fresh carbon and GFO or something like Chemipure Elite in the HOB if you are not already. You may have to change it frequently to start but once you get the tank/odor under control you should be able to stretch that out to weeks.
Your solid rock is a bit concerning. 8 lbs of solid rock isn't gonna cut it long term. The lb per gallon rule (which I feel is a bit much) is for porous rock which provides adequate surface area for beneficial bacteria. Having solid rock, your bacteria population is likely cut in half (or more) of what it could/should be.
Flow is another concern. I'm sure your HOB is turning your wate over but you really have to countercurrent to suspend wastes and detrtus so the HOB filter can capture it. In addition, the organics that feed the bacteria are getting less contact time with the beneficial bacteria that you do have.
Don't put a lid on the tank. You'll just end up cleaning the top and you'll likely have heat issues. Lowering your temp to 76-78 might help too BTW. Interested in knowing what your ammonia, trite, trate and phosphate numbers are.
The next suggestion would be to run fresh carbon and GFO or something like Chemipure Elite in the HOB if you are not already. You may have to change it frequently to start but once you get the tank/odor under control you should be able to stretch that out to weeks.
Your solid rock is a bit concerning. 8 lbs of solid rock isn't gonna cut it long term. The lb per gallon rule (which I feel is a bit much) is for porous rock which provides adequate surface area for beneficial bacteria. Having solid rock, your bacteria population is likely cut in half (or more) of what it could/should be.
Flow is another concern. I'm sure your HOB is turning your wate over but you really have to countercurrent to suspend wastes and detrtus so the HOB filter can capture it. In addition, the organics that feed the bacteria are getting less contact time with the beneficial bacteria that you do have.
Don't put a lid on the tank. You'll just end up cleaning the top and you'll likely have heat issues. Lowering your temp to 76-78 might help too BTW. Interested in knowing what your ammonia, trite, trate and phosphate numbers are.
I have enough movement with the airpump and filter though.
