need some advice, my levels are all screwed up

[amyrs2880]

Hello. I am new to the site this is my first post. I am having a lot of issues with my 20gal.
I just moved several weeks ago, and i was extremely careful with my fishtank and i saved about 90% of the water. after a couple of weeks of being in my new place my guppies start dying...about one per day. so i have some test strips that i used and here are the results. nitrates are good. nitrites are off the chart. my water is very hard (it always has been because of where i live). my alkalinity is low. however my ph is extremely low and there isn't an accurate number because the color on the strip is bright yellow and the lowest one on my chart is an orange yellow which is 6.2 so i know that it's very low.
i did about a 30% water change two days ago and the test is still the same readings.
my tetras, catfish, and otto are not bothered by water levels, but i only have one guppy left now. they died very quick and suddenly.

so does anyone have any ideas about all these weird levels? i have two live plants in my tank. the temp is always great.
what i really don't know is what my levels were like before i moved, but i have had all of these fish between 2 and 5 years. and they were not stressed terribly by the move-and it was actually their 2nd move in their life. so if anyone has some thoughts or ideas I'd greatly appreciate the advice as i really do not want to lose anymore fish!
thanks a bunch!

Amy.

 

[Newman]

1, dont rely on the strips and get liquid tests for pH, ammonia, nitrite, and nitrate. (ou can also get GH and KH liquids if you care for those)

2. The first indication that your stirps are decieving you is that all of those fish should die within the next 24 hours if you nitrite is "off the charts" nitrite is even more deadly than ammonia and will kill fish if its anything above 1ppm or so.

3. what are your readings in terms of pH, KH and GH of your tap water (make sure o AGE your tap overnight to get accurate readings; as tap water tested directly would have a lower pH than it would if it was sitting in a tank of water.)