It sounds like you're getting it worked out.
Just for a reference, I have 11 medium to large cichlids in a 210 gallon tank that I feed twice a day. I do a 90% water change on this tank every Friday. I pump the water out of the tank with a siphon hose hooked to a water pump (Mag Drive) that runs straight to my bathtub via 20' of flexible tubing. Once the tank siphons down, I turn on the bathtub faucet, adjust the temperature, stick a bucket under it, and drop the Mag Drive pump into the bucket. I add a little over two capfuls of Prime (I use the big bottle, so one capful treats 100 gallons) directly to the tank, then plug in the water pump and stick the end of the hose in the tank to refill. It takes an hour or so to do all of this (depends on how powerful your water pump is) but there's really only about 10 minutes of actual work. The best part is that there's no heavy lifting with bucketfuls of water. Keep in mind that my pH does not change once the water ages -- it's the same from the tap as it is in the tank. Some people have water where the pH differs from the tap vs. aged, so it'd probably be a bad idea to do such a large water change using this method if that were the case. You don't want them to have pH shock.
You can pick up a relatively strong water pump for about $60 online and the non-toxic potable water grade flexible tubing is sold for a few cents per foot on most aquarium sites. I think you can also get it at places like Home Depot, but I always order all my fish supplies online. You also have to get male and female adapters for the water pump so that the tubing and siphon hose will hook up to it. Still, for less than $100 you will save yourself a ton of time and labor, especially if you have multiple tanks!
Anyway, the point of all that is my tank needs those large water changes or I'd run into water quality issues real fast. My nitrates still creep up really quickly, so I try to avoid going over a week. It'd actually be better if I did them a couple times a week, but I have so many tanks that it's hard to do that. Your biological filtration should be taking care of ammonia and nitrite, so your big issue right now is probably nitrate, and all of the dissolved organics that come along with fish waste and leftover food. Filters will not remove those and chemicals are really just a band-aid. The best way to take care of them are water changes. Don't let them scare you -- if you get the right equipment (water pump, Python siphon system, etc.) they are pretty easy and painless. Your fish will thank you for it.