I use amquel, which controls ammonia, nitrites and it has worked pretty well. It will still show up as positive after you use it, but the ammonia will be neutralized and not harmful and your biological filter should clean it up. I also have .25 mg in my tap water and that is the threshold for "safe" in many areas, even though if you have someone chronically ill, they recommend they not drink the water. You can consider a charcoal filter or aerator tank if you have well water, that would treat the house.
On your tanks, overfeeding is a cause of high ammonia, not cleaning the gravel, improper or inadequate filtration, and changing filter medium too often. I alternate filters, I have two sets for each tank. When one gets clogged, after three weeks or so, I rinse it in cold water brushing off some of the biologic material and old food. Then I swap in a new filter. If there are two cartridges in your filter, I would change one one week and wait to change the other until a week later so that it can transfer some of the good brown stuff to the filter. Also, having rockwork and gravel and air in the tank can help alot with ammonia. I use crushed coral in all my tanks which buffers the water, raises the pH which helps keep the ammonia less harmful. I have rocks in my tank that get brown algal type growth on them and I only ocassionally rinse them, so as not to kill the beneficial bacteria on them. I'm not real anal about brown algae on the tank walls so much, though I like the front to be clean. I do vacuum and do water changes biweekly and add the amquel with each water change. When I change the filter cartridges, I replace them with the old ones I took out and cleaned. This has worked really well for me. Eventually, as they wear out, I buy new cartridges, working them in one at a time.
I also started my tanks by adding a biological booster, which is controversial, but I think it shortens the time frame for breaking in a tank. You might consider adding some by pouring it into your filter, since this is where you want the growth. Cleaning too much can cause problems.
On another note, the type of food you feed is very important. If you are prone to overfeeding with flake, pellet might be a better choice. It is certainly easier to get out the extra food. Many new foods have a lot of oils in them which seem to effect the water negatively if you don't skim it off, so I try to avoid food with lots of fish oils or that makes the water oily.
If you have live plants and have dead plant material, you may want to question whether they are worth the hassle because you need to keep that dead material picked up too. Adding extra zeolite in a bag, or bioblocks or a sponge prefilter on your intake can help.
Probably a quick easy fix might be to add a bubble screen across the back of the tank, you know that cascades lots of bubbles. Extra aeration helps alot and they look cool and the fish like them. Even some airstones might help, but the bubble screens really work well to aerate the whole tank quickly. They are a blue tubing that is porous that runs across the bottom of the tank. It helps my tanks support my fish load and keep the bacteria growing well.
I hope that your fish are okay. Adding air I think would be a great first thing to try, along with making sure you are adding an ammonia neutralizer of good quality. Oh, I think you need to change the zeolite in the media basket often, but charcoal less. you might try a mix or add some biobeads. A sponge prefilter on the intake helps with these filters.