I don't mean to gross you out, but could you pull the filter pads/cartages out sooner and rinse them? It sounds like they are doing an excellent job (also) as mechanical filters. It might be better to remove the "big pieces" of food or whatever, which get caught upon them. The action of the water and the microbes in the tank will begin to break those larger items down (first into  some ammonia). That adds to the nutrient soup in the tank which could encourage that cloudiness.

In a certain sense I hate to make suggestions, because you are doing such a magnificent job of doing all of those things. I'm sure you have wondered if "no good deed should go unpunished."

An old buddy of mine called up yesterday and we spent a lot of time talking about some problems in their son's new fish tank. He did a lot of things right, moving in the gravel from a smaller tank, etc. His big mistake was the old classic of buying far too many new (unquarantined) fish and blowing up the capacity of the tank to cycle ammonia.

As we went over what had happened, I was reminded of an observation by my biology teacher that all sorts of things within an animal's system and within their larger environment are based upon equilibriums. By adding so many new fish to any aquarium, we really upset the equilibrium established by the fish and the beneficial bacterial cultures.

It is sort of like when we are ill and are prescribed some really powerful antibiotic. It "gets" the bacterial illness that is afflicting us, but also kills off most of the useful bacteria in our digestive systems, which enable us to digest food. Then we may have to deal with a horribly upset stomach and the banshee-two-step.

And after Christmas, when I look at the balance on a couple of charge cards, I wish there had been a better equilibrium between payments and expenditures. :(

When the filter is changed, are you using the filter pads as biological filters (home for beneficial bacteria) or as chemical filters (for a week or so the activated carbon removes ammonia)? Of course we may use them both ways and, if the edge of the bag/ insert is stopping "big pieces" it is even a mechanical filter.

I wonder if a brand new dose of activated carbon pulls so much ammonia that the beneficial bacteria starve. Then in a week, when the activated carbon is "used up", there is more ammonia in the tank. Probably that is not the issue here though.

You are just rinsing the filter cartridge and returning it gray to the tank? That gets rid of the "big pieces." That way, all of the beneficial bacteria in there isn't washed away. White filter media means that it is sort of sterile or without any beneficial bacteria. Then you are restarting a part of the cycling process.

What you are doing is great but rinse the filter, not blast it spotless one week. The next week or interval, gravel vacuum 1/2 of the tank. The third week, do the other half of the gravel.

The water changes, if the water is previously treated and sits open a while, are wonderful. (Water treated in the tank may already be wiping out beneficial bacteria.)

If we see the whole aquarium as one big bio-filter (or biological system), that way the majority of the beneficial bacteria in the gravel and filter are not taken away all at once. And if there is enough beneficial bacteria in the gravel and filter then maybe the cloud, a bacterial bloom, will not form in the water.

I know that cloudy water is unattractive and I too would work to prevent it. However if the rest of the tank has been so thoroughly cleaned, maybe you are lucky that so much is being done in the water. :)