r/Amphibians

I have some questions regarding our axolotl's low KH. I have been doing 25% water changes to lower our Axolotls nitrates as they were showing way too high. I was reading from the top of the test tube vials which darkens the colour, however the reading I was getting was looking like 160ppm. Now it is reading 40-80ppm, I think it is 40ppm.

I started having issues with the KH test bottle. Sometimes it would reading 0-1dkh (what I was thinking the water is) and other times it's reading way way higher (the tap water is typically 0-1dkh from a test I did in the past and now it's reading 13+ drops!) I think it is because I didn't let the test tubes dry in between chemicals, therefore the results are being skewed. I think the tank water is very low, potentially even 0dkh, after the water changes I did with our super low KH tap water.

I've read that the nitrogen cycle process eats up KH and a can cause a spike is ammonia and nitrite and a crash in PH. The way the tank typically gets cleaned is at using a net to swirl around and suck up the waste/food. I'm worried that this would cause a spike in ammonia and therefore get rid of the remaining KH buffer due to the nitrogen cycle increase from the excess ammonia and cause a PH crash/ammonia or nitrite spike. Is this true? Should it be cleaned in a less disruptive way? The siphon we have I previously hosed out with the outdoor hose, I later learned that the outdoor hose had been used for a job including a pesticide/herbicide/fungicide spray, I'm not sure which. A hose end sprayer was used, and I know there is a potential for the chemicals to get sucked back in. That was about 4 months prior and the hose had been used since however. Would the siphon be well and truly safe to use? I'm sorry if this is a stupid question, I just don't know how easy these chemicals are to rinse away.

Should I continue with water changes to get the nitrates in the oranges not reds to ensure the Nitrates don't rise again, or should I focus on raising the GH and KH first? If I leave it too long before another W/C I don't want the Nitrates to rise too high and need to do even more water frequent water changes with such a low KH and GH.

My final question is, if the tap was treated with something to raise the KH, would it risk causing a swing and crash on low KH if the additive the municipal water supply used dropped down/wore off? (I have read that Soda Ash, which our municipal uses to raise PH does.)

I'm sorry if these were stupid questions again, and thank you so much for any advice in advance!!