Try leaving a bucket of tap water for a day and then retest it to see what the KH is then. I have a feeling there's something not quite right with either your tap water or your tank set up. What substrate are you using in the tank and are you adding anything to the water?
Im using eco complete substrate. I might add some ph buffer but thats it. I think it's my tank this morning checked the ph and it went down to 5.2 from 6.1 last night. I know ph goes down at night but by that much?
I am adding co2. I think the PH level was at 6.2 after a water change. Then when settled in it dropped back down. I just got a PH monitor and will try to keep a closer eye on it. I believe my water just doesn't have enough buffering power. I will try to raise the KH to help with that. For the GH test kit i'm using a all in one dip stick. I know there not the ones most people use I will try something else.
Your numbers don't make sense. First off, be sure your test kits are accurate. Prepare some standard solutions and see how accurately they read. Keep in mind that there are two ways to measure hardness - in degrees and in ppm (parts per million). To get to degree from ppm divide by 17.4, so your gh of 200 converts into about 11.5 degrees of hardness for gh.
You're using Eco, which typically will RAISE kh, not lower it. So your kh dropping makes no sense! This, again, makes me wonder how accurate your measuring kit is.
If you have city water, just get a report from the municipality. It will tell you all you need to know, and then some, about your tap water.
As far as raising your kh for CO2 dosing, this is a belief that is quickly losing followers. There are many hobbyists out there with kh1 water who do not add bicarb to raise it, and have great tanks, and happy, healthy fish.
yes I am using sity water. I don't undertand the kh drop either. My tank was doing great then I had a crash due to some meds i needed to use. I took the plants out at that time. Now about a month later I have been getting a lot of diatoms on the glass and plants as well. I just bought a presureized co2 system before that I was using the carbo pro. Didn't really seem to do much. But my plants were growing and seeding. I have never seen this so called pearling in my tank nor have I had much experience with live plants. I wouldn't say my tank is stocked heavy. I don't want to add more plants if I can't grow the ones i have now. Right now my newly calibrated co2 checker is in the yellow color and hasn't gone down over night even with lots surface movement. Last time this happened it took a week for it to get back into the green level. How often should I vacumn the sand or should I never do that?