Shockingly, I agree with him on some points.....
I also agree with Miss Wiggle, you are not at fault here, it's your dad that is getting out backs up a little bit....
FILTERS; you can run a system without filtration. It is however
very hard to do. To run such a system, you would need a very in-deapth knowlage of how a wild pond or similar situation worked, and also understand why nature does it that way. These systems are only realy for advanced aquarists. I have 14 years fishkeeping experience behind me, as I wouldn't even thing of trying a system like this; with 5 years of reading about them, I still don't have the deapth of knowlage to design such a system, let alone run one...
WATERCHANGES; again, can be done monthly if you are "savy" about them. To get away with monthly changes, you need a very light load on the tank, and the monthly change will usualy need to be large
Temperature drops are nothing to worry about. I fill direct from the cold tap, even when doing 50% waterchanges, even during mid-winter. It takes an hour to fill, and the temperature drops about 5 degrees, and isn't a problem. Raising the temperature IME is an issue. When the temperature drops, I usualy see my plecos trying to breed, so I can't see how these "negative effects" are effecting them
LFS STAFF WORKING ON THE FORUM;does happen. I work in my LFS, but I don't recomend treating fish without good reason. Fish treatments put the fish under a great deal of chemical stress can can lead to premature death, again unless you are treating because it's nessisary, and leaving is something that will do more harm than good. My med recomandations are only made when I'm sure all other methods of treatment have been exhaursted.
MEDICATIONS; Water conditioner is not a med. When you farther was a boy, he could leave a bucket of water to stand for 24hours and then use it, as chlorine would gas off. Now water companies are usig chloramine that stays in the water for years. This is why we now use water conditioner. Some members that know their water company use chlorine, will not use water coditioner. Miss Wiggle was one such member for a while. US supplies though are almost always chloramine treated these days, chlorien is the exception to the treatment routien...
If your dad realy knew his stuff, a tank could be ran his way. He however will likely crash your tank killing most, if not all, your fish, as the knowlage isn't there to support his methods. Brace yourself for losses, in his care there will be many
RE; Test Kits. Strips are un-reliable often giving false highs. Your tank may well have been cycled before "dad" took over, but you won't be able to tell without liquid kits. I agree that it is impossible for there to be zero ammonia or nitrite in the water, but the levels should be so low, that out kits see them as zero. If 4 is a good number for ammonia, perhapse he could explain why my test kits show zero for ammonia and nitrite, yet my discus that are amongst the fussyest fish arround for water quality, are still alive and well???
Some bacteria will live in the gravel, but the ammounts will be neglagable, compaired to the filter colonies. Bacteria in the filter will account for 99% of all the tanks bacteria when the system is mature. Biofilm will acount for about 0.9%, leaving about 0.1% of all the tanks bacteria in the gravel
In all honesty, as this point, I'd touch, but only to remove the fish and take them back to the shop. At this time, it would be the fairest thing to do for them. If they stay in your dad's care, their days are numbered
Best of luck
Rabbut