Safe levels of waterchanges?

That level of nitrate won't hurt your fish but how are the *nitrites*? I'm sure the others here will tell you the Bala is going to outgrow your tank pretty quick but other than it, I can't see that you are particularly overstocked. You probably did have a minicycle but without checking the nitrites, I don't think we can tell if that is finished. The level of the nitrate increase may be saying that it is but that is just a guess. If your nitrates are going up that much in one week, I'd watch carefully not to overfeed.

Oopsies, me bad and it's too early.. Red Tail, not Bala. Not sure how big those get..

You can change substantially more water weekly than you do. You can do it by either doing more frequent changes on the scale you currently do, or by doing a larger percentage change. If you add dechlorinator prior to refilling with the Python - and stir it around to dissipate it with the tank water - chlorine shouldn't be a problem. Unless your tap water is dramatically different in composition from your tank water, I'd not worry about it.

Another thing to check: what is the level of nitrates in your tap water? Ours often is in the 30 ppm range (we're in an agricultural area), so keeping a tank at 40 ppm is pretty good for me. Personally, I don't think that even long term exposure to 40 ppm nitrates (and whatever other dissolved organic compounds go with it) will hurt your fish.

I would keep an eye on nitrate, though, and make sure it doesn't creep up over time. It is not uncommon for a tank to read very low nitrates when it's first set up (after cycling) but for that number to stabilize at some higher value after a few months. Just be sure it doesn't keep creeping up.

The points others have made about the bioload are sensible, too, particularly re: the Bala.

Good luck,
Jim

I agree with the above posts.
The fish load in your tank looks OK, so it doesn't seem to be the problem. One thing I'd do first is to not overfeed. Feeding lightly once/twice a day is usually sufficient. Even one day "fasting" for fish is sometimes recommended.

As Jim mentioned, 40ppm is not a major problem in most cases, unless you have very sensitive fish such as Discus, or blue rams, for example. Your fish are hardy enough that it shouldn't be a problem.

Another thing I suggest is to vacuum the gravel when you do the water changes (if you're not already doing it). Plus, rinse the top part of the filter media (the part that gets dirty the most) in the vacuumed aquarium water. Do not rinse in tap water as it will kill the good bacteria. If the dirty filter media is left in the filter too long without cleaning or replacing, it will tend to increase the nitrates.

HTH